A file that size is most likely containing something you don't want.. I'm not entirely sure, but I do think you should run your antivirus program, Spybot and Adaware.
Best to check out the online virus checker too if yours doesn't find anything...
http://housecall.trendmicro.com/hous...start_corp.asp
Also go here and do this scan too...
http://www.windowsecurity.com/trojanscan/
Hope you come up clean
