There are several new Trojans for vista and you can do several things to eliminate them.
run hijackthis and generate a report,this can be assessed and you may get help here or at bulldog antivirus forums forums (Touch would help you there amongst others and he is good).
From practical experience with Vista which seems to be the most targeted of the windows systems at the moment,I know Nortons/symnatec have come out with some new definitions in regard to Vista Trojans just recently and although not my favorite anti virus would update it if you have it.
I personally wouldn't touch Vista with a big pole until they have worked out all the teething problems with it as they have with xp and it`s only taken them 9 years to get that right.
The next windows release will probably be in conjunction with Linux as they are collaborating now in that regard,then it might be worth more than its inflated price and vulnerabilities.
Also read what disk contented had to say and check this link
http://www.auditmypc.com/process/mssvr.asp from your description it does sound like ms server issue as link describes,although may be renamed to appear that way as well.