google actually for the ones I don't know already
I just put in the name of the exe/service and then check each of the first coupla pages of results. (I never rely on just 1 or 2 reviews of these things)

a long time ago I learnt one of the major slowdowns for a machine is all the crap some programs love to have running just for them. printer drivers that load 'one touch' scanner addons (which you use like once a month), Adobe's PDF reader that leaves a app in ram 'just incase', winamp agent or .....the list goes on and on....

this stuff soon bogs a computer right down.