In the lower right of Task Manager...Processes tab is a button to show processes from all users - it's use is essential to find out the total of what's running on your system. When you don't use it, all you'll see is the processes that your user account is using - which won't total up to 100% for the entire system.
In the Processes tab the 2 most useful columns for identifying stuff are the Image Name and Description columns. If they don't tell you which is which, then you'll have to a bit of searching to find out more.
First try the Bleeping Computer Startup List located at the tab on the top of this page (here's a link to it:
http://www.bleepingcomputer.com/startups/ ) If you don't locate it there, then it's off to Google to search for it.
Many Google results will claim that "it" is a virus - take that with a grain of salt. I like this site for most of my research on startup processes:
http://www.liutilities.com/products/wintas...processlibrary/ Once that's done, and you know what's doing what on your system, it's off to the Services tab to see what you can keep and what you can kill. To do this, go to
http://www.blackviper.com/WinVista/servicecfg.htm and read everything you can about the Vista services - and then apply this to your services that are running. To do this, you'll have to click on the "Services" button in the lower right corner of the Task Manager - Services tab.
You can Start and Stop services from the right click menu in the Services applet - but you'll have to select "Properties" in order to adjust their startup behavior. In the Startup type dropdown box will be several choices (which Black Viper explains much better than I could). Select those as appropriate and reboot to verify the changes (or you can Stop the services one-by-one to see the effect that it will have).
And, just to confuse things further, keep an eye on the Performance tab and the Resource Monitor (a button in the Performance tab) to keep track of what's going on.