Nice one. Your now free from infection?
I'd advise you keep microsoft antispyware on and makesure that its security agent status is set to enabled.
Also, and this is very important, goto
http://windowsupdate.microsoft.com and check for security patches.
Now download and install ie-spyad
https://netfiles.uiuc.edu/ehowes/www/resource.htm#1v2
What this does when installed is put a great list of dodgy sites into your restricted sites area in internet explorer, meaning that if you visit those sites then pretty much everything from them will be blocked. Keep this uptodate as the list changes regularly.
Also in IE do Tools>Internet Options>Security Tab. Click on each zone in turn (eg Internet, Local intranet etc) and click Default Level for each one (if it becomes available). What you often get is spyware resetting the default levels for these zones.
Also in the same bit, click on trusted sites and look through the list, if there is anything there that shouldnt be then remove it.
Now when you browse the web, you may find that some sites will no long seem to work quite right, for example they won't persist your login name - if this happens for a site you trust, just add it to your trusted sites zone in the list above.
Antivirus ofcourse with up to date sigs, but think you have that allready.
If you wanted a change, you could move to opera or firefox as a browser, but I personally think that as these become more popular they will be more of a target for malware.
Final bit of advice, get a hardware adsl router/firewall. You can get them for about £60 now with statefull packet inspection firewall built in - would of been lucky to get that sort of thing for £500 3 years ago.
I do the above and havent had a single problem since ive instigated those changes, and thats running 2 servers, and 6 PC's, plus my gf's pc.