Grisoft (Makers of AVG anti-virus) has a free spyware scanner and removal tool that will catch a lot. I've seen some free registry scanners but I don't really trust freeware that deals with such a crucial part of the system. You could buy something but I rarely buy software tools, just me being cheap, but with my technical knowledge I can always recover if anything slips by my free virus scanner and spyware scanner. I may lose some files in the process, but I don't have any files on here that are worth more than $50, so why pay to *maybe* keep them safe?
Also, I dunno what kind of hardware you have, but adjusting some Windows GUI settings, like mouse shadow, animated menus and minimize/maximize, that will speed you up a little, but not that much if you have a newer computer. You could check your background processes and take unwanted stuff out of the taskbar and auto execute at logon, if you know how to determine that stuff. If you want to try and figure it out, it's in the Windows home keys menu (Ctrl+Alt+Del), and the Startup autorun list is in Run: msconfig. Don't mess with that list if you don't know what the processes are that you want to turn off.
