Try running Spyware Doctor, Ad Aware or Spybot search and destroy. There's plenty of other spyware apps out there for you to try as well. http://www.pctools.com/spyware-doctor/
Quite probably. Still, at least you've addressed it now.
Also if it's still going slow, you may want to try a disk cleanup.
Start ->All programs -> accessories -> System Tools -> disk cleanup.
I'd have to disagree with neil on this
and say NEVER use an online scanner ....
unless you see it specifically endorsed in one of the PC mags
you just never know what giving a website access to your PC will lead to
Phishing is everywhere .... even on the download sites so you can never be 100% certain
but just because you end up with 1000000s of positives .... it doesn't mean that the scanner is good - or better than the one which only showed 10..... it just means it showed more entries
more than one of the "try before you buy" scanners are classified as trojans because they tell you you are infested
you just never know where it's actually coming fron