SOLDIERX.COM Nobody Can Stop Information Insemination

I have a second computer with 4GB RAM, running Win7, with 160GB HDD, dual-core Intel processor, and absolutely NO anti-virus features.. I've been using it to test out several old versions of viri - and discovered many of these old viri revisions (certain koobface releases, rogue A/V malware, etc.) just have no effect on the new and more powerful operating systems. My question to you who dabble in virus creation: How do you keep your viri from becoming obsolete in the future? Which precautions do you take to keep your virus from being ineffective as soon as the next service pack hits?

Just a few questions from a curious FoRM.