Maxpower, yeh I use the Vipers settings and such but End it All does still kill a few backround svchost task that aren't critical when your playing online.
Also Tweaktowns XP guide
is excellent for tweaking XP to its full potential.
And if you really want to dig down deep into the system and tweak the hell out of it use their advanced guide over here.
End it All is good for games that use punkbuster as well.