few things..
Symantec's site says, if you find MSBLAST.EXE on your system, you have been infected.
it's doesn't only "harm" Windows XP and Windows 2000, it also harm Windows NT 4.0, NT 4.0 Terminal Services Edition and Windows Server™ 2003..
those who you use Win98SE or ME or whatever else you MAY get a worm warning, but it wouldn't harm their OS.
it hits your TCP port 135, and it causes rebooting problems and sudden shut-downs (approximatly every 10 minutes).. you can read more of it's effects on the given site about the vulnerability patch..
if you don't have it, update your AV program, FW program and use the Windows Critical Update..
if you have it already, you need to scan your computer using the FixIt (mentioned above) then the RPCvulnerability Patch according to your Windows version.. (from here:
http://www.microsoft.com/technet/treeview/?url=/technet/security/bulletin/MS03-026.asp).. if you don't know your windows version, press START-> run-> winver..
after using the fix and patch do all neccessary updates, as mentioned above..
pay attention, on this saturday there is ANOTHER worm attack.. be carefull..