According to Symantec;

Systems Affected:  Windows 2000, Windows XP
Systems Not Affected:  Linux, Macintosh, OS/2, UNIX, Windows 95, Windows 98,
Windows Me, Windows NT
http://securityresponse.symantec.com/avcenter/venc/data/w32.blaster.worm.html

Please state the source of your information

If you believe that your system has been infected then you can do a manual
search for the infectious files and delete them manually. It will crash
systems that it cannot properly infect.

There is no patch for Windows 98/SE as it is not affected by this worm.
Win98
does not have an application called TFTP (Trivial File Transfer Protocol)
service using TFTP.EXE.to help the worm complete it's quest.

Symantec site also says; "Users are recommended to block access to TCP port
4444 at the firewall level, and then block the following ports, if they do
not use the applications listed:
TCP Port 135, "DCOM RPC"
UDP Port 69, "TFTP"