Have a read of Spybots news articles. Then you'll see stealing definitions isn't a good thing.
What would be better is if you program something which removes MSNM specific viruses and shit. You could make it update the definitions from your site. If it did it's job properly and was pretty professional you could have a pretty good program going for ya.
Something like this but for MSNM:
Aim Fix 1.0 (
Mirror). It would be a good learning experience and definately a lot simpler than doing it for ALL spyware/adware/malware etc.
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