registry editors are great, some auto find entries that point nowhere and offer a console to delete these entries.
but never discount manual registry editing, slow but allows you to find things that shouldn't be there, annoying spyware infested so-called shareware programs you are trying out, also a nifty method of removing trial softwares entries so you can reinstall again and go through the trial period again if you feel you didn't get a good look at the program during the original trial period!
one thing i don't do though, is memory optimisation. really not worth the hassle as it can change strings that windows cant normally change giving hard drive access errors in the worst cases. if you want more memory, right click under your task bar icons and choose Task Manager and then Processes and have a real hard look at what is running on your pc. then install a Startup Manager that allows you to change the programs that startup when you boot your machine.
all these functions run in a great program called Tuneuputilities2004, best all in one program i have ever tested, just don't use the memory optimisation, bad for your girlfriend (oop,s pc! same thing
)
one final thought. Sygate Personal Firewall is free for home use, pretty much solid as is without buying the Pro version. i am one of the 92% of people i know who is still using or has regressed to service pack 1. service pack 2 has major, major issues and it only really tries to patch the holes a mature software firewall does, although you do get some little gimmicks like auto recognising USB flash drives, (like, who can't shove a disc in and install the drivers for that!) and windows firewall coming on each time you boot (well, Sygate negates the uses of that!) downsidesof sp2, everyone had to patch things, like symantec products not working, there went nortons anti virus updates! the game unreal tournament 2003, (i believe still doesn't work) all your hardware now needing new drivers, when there weren't any out there!
so, until Longhorn, service pack 1 with some choice updates (auto updates turned off!) free anti virus better than nortons and good mature software firewalls will be my fortress protection