I still use WinXP and I keep the windows security essentials up to date.
My PC has been getting a tad slow over the last few days so I d/led Ad-Aware 10 (free) from http://www.lavasoft.com/
After running a full scan which took 5 hours it found 11 threats; 1 of them a Trojan named Trojan.Win32.Generic!BT.
Its defention can be found here… http://www.lavasoft.com/mylavasoft/malware-descriptions/blog/backdoorwin32poisontrojanwin32genericbt
Well its in quarantine now but Im pretty sure this little critter got past windows security essentials.
Just a heads up.