David: Microsoft has a program called TweakUI that is very handy. It can make your machine auto login again. It provides easy access to some hidden registry values that are very useful to tweak (And does so in a safe way)
I agree with you totally. Any user that installs a lot of crap can majorly slow down/unstabalize their machine. AS a tech I see this way too often. "My computer is so slow now..."
Unfortunately too many useful program do this, and some are even preloaded for you when you get a new PC. I tend to format and do a manual install whenever I get a new PC to get rid of Dell's/Gateway's/etc's advertise crap they install for you that can cause slower unstable machines.
If you are unfamilair with registry areas where program auto run from their are also useful tools to look at those area and check/uncheck them (Rather than just removing the registry line and being screwed if it was soemthing you needed).