Hi Alex.

Sometimes the thing is not to run a patch and relax, there are other tasks to do in order to eliminate the thread, i recommend you visit this page:

http://securityresponse.symantec.com/avcenter/venc/data/backdoor.litmus.203.b.html

Just follow the instructions, usually patches don't clean the registry from these threads, go to this link and follow the instructions.

This SVCHOST.EXE appears to be in many worms, not only the welchia Drazen told you, check if your antivirus is updated against these worms and new viruses.

Hope this helps.

Jim.