The best way to speed up your PC is to give it more available memory—but freeing up as much of the memory you already have is cheaper and easier than cracking open your case to install a new stick of RAM. It takes a lot of memory to get a modern Windows system up and ... well, not doing anything in particular, really. Between cryptic system processes, confusing "helper" applications, and background utilities, a whole lot of who-knows-what gobbles up memory and slows down your work. While a lot of programs claim to optimize memory use and pare down processes, Windows' built-in Task Manager can do the job just fine, given the right tools and know-how. Today you'll extend and empower Windows' Task Manager to speed up your system by cutting out unnecessary memory hogs.

See what's running

Hit Ctrl+Alt+Delete in Windows 2000/XP (or Ctrl+Shift+Esc in Vista) to pop up the built-in Task Manager, which offers a pretty decent look at what programs you're running, as well as current CPU and memory usage for each and a basic description. It doesn't, however, tell you whether Windows will keep working if you kill one of these processes, and descriptions of the "Windows host process (Rundll32)" variety can be more than a little frustrating.

Our first stop is to download the Quick Access Infobar, which adds a link next to each process to a relevant search result from the ProcessLibrary.com web site. The ProcessLibrary site won't know anything specific about your "rundll32" or "svchost.exe" entries, but for most common processes ending in .exe, you'll get a read on the program it's connected to, and whether or not you can live without it.

Once you've found a few processes that don't need to be running every time you start Windows, disabling them is pretty easy. In Windows XP, first check the "Startup" folder in Start->Programs. You can also use the System Configuration Utility's startup manager: enter msconfig into a command prompt or the Start Menu's "Run" box. (Here's more on msconfig usage posted here at Lifehacker, and for more help on XP pruning, check out this CNET tutorial). In Vista, head to the Control Panel, choose "Change startup programs" under "Programs," then click the "Show for all users" button in the lower left to enable disabling or remove startup programs.

Go slowly here—make one or maybe two changes at a time, then wait until after a restart to make sure everything is still working as it should. Overall, the "Startup Programs" list shouldn't let you make critical, system-wrecking changes, but don't make the change if you don't know what it affects.

Dig Deeper

You've knocked out iTunesHelper.exe and a handful of other unnecessary apps, but what about those more vaguely named items? To find out, grab Process Explorer, a kind of super-charged Task Manager. It looks a lot like its built-in counterpart, but provides a great deal more info. Blue and purple highlights are applications, while pink rows are Windows services. You get process names and any companies matched to them, but lets get deeper. Right-click on one of the column headings (or hit the "View" menu) and choose "Select columns," then check the "Command line" option.

Now you'll have an extra column on the right, with the full path ("C:\Program Files\WhateverProgram") to where each process is launched from. Mouse over a "rundll" or "svchost," and you'll see which services are launched under that container. Double-click on a process, head to the "Threads" tab and you can see which service is using how much CPU power—obviously something you want to stay up on, especially for non-important services.

Found a service eating up memory for no real benefit? Double-check that you can go without. The Black Viper site has lists for each Windows system, showing you "Safe," "Tweaked," and "Bare Bones" service configurations, along with what's turned on and off by default. If you're still confident you can turn it off, right-click on a service, choose "Properties," then set its "Startup Type" to "Disabled."

Kill bad processes before they crash

Even if you've chopped down your system to leave only the leanest, most essential processes running, certain programs (I'm looking at you, Firefox) can sometimes go berserk on your CPU or memory, sometimes right before crashing the whole system. But choose from any of our previously mentioned app-watcher tools and you can enforce martial law on your motherboard.

• Process Lasso: Watches your CPU usages and sets processor-hogging apps to lower priorities, as well as offering lots of customization for auto-start programs and other throttling settings. Takes up 10 MB of memory itself, but offers lots of task management.
• Task Killer: Lighter-weight (as in 1 MB during use), system-tray-seated app that allows easy killing of failing processes.
• AntiFreeze:
  Hit a key combination to suspend all your running processes and then restart them one by one, ferreting out the crash culprit in the process.

More Task Manager Mastery

Here are a few more tools and tips to help you analyze and control your system's memory usage, all of which can be experimented with a bit more freely than the changes we just ran through.

• Set up multi-kill batch files: Got a handful of programs that you frequently find yourself cursing at? Need to quickly slim down your memory profile for an intense app or game? This quick tip will show you how to can quit multiple programs with just a double-click.
• Learn the difference between Windows' two memory types: Both Task Manager and Process Explorer can detail a program's use of "Working Set" and "Private Working Set" memory—umm, wait, what? This CyberNet mini-tutorial should make it a bit more clear.
• Start Task Manager in the Tray: If you're running through multiple reboots while testing your optimization tweaks, having Task Manager just one click away can save you a fair bit of time.
• More process checkers: If you've found a background application that the ProcessLibrary site just can't identify, try these other sites: Tasklist, WhatIsThatFile.com, and the Uniblue ProcessLibrary (search box on the right-hand side).

How do you keep your Windows machine running light and fast? What built-in processes and apps have you found pretty much useless? Go ahead, call them out in the comments and share any other hard-won memory-freeing tips.

Kevin Purdy, associate editor at Lifehacker, likes his Windows like he likes his kitchen—fast-moving and simple. His weekly feature, Open Sourcery, appears every Friday on Lifehacker.