..... the computer
must be free from infection before upgrading to Service Pack2 (SP2)
However if seeking assistance to remove malware, it is critical that you update to Service Pack 1a.
Get SP1a here :
http://www.microsoft.com/windowsxp/downloads/updates/sp1/default.mspx
Although Windows XP Service Pack 2 is cumulative, meaning it includes Service Pack 1 and all updates predating the release of SP2;
before you upgrade to Windows XP SP2 (Service Pack 2) you must ensure the computer is free of malware.