Hi, it def sounds like a variant of MS/blaster. I had a new variant last week.
First thing is to activate your firewall in xp if not done already. If you have firewall software then use that, I use Zone alarm Pro 4 from zonelabs. If you dont have any firewall software you can use winxp's. activate this by clicking network neighbourhood. Click on view network connections, right click on your internet connection and select properties. you then click on the last tab and in there, there should be a tick box for activating your firewall. Click it.
ok now click on this link which will download a scanner from symantec to search for the worm. http://securityresponse.symantec.com/avcenter/FixBlast.exe
This is the removal tool not the protection. you then get a link from this tool when its finished to MSs website. From here you need to install the latest MS security update which will stop it happening again with help of your firewall. Never surf or connect to the internet without a firewall on!!!!!
have fun and hope it helps.