When it comes to SEO..your keywords determine your position..the TLDs are always the next criteria..also, com and net are both pretty good when it comes to SEO..but if you were comparing something like a .com to a .co.cc or something..results would have been pretty different..
.net is a good choice, especially if you find a direct keyword .net that's available. It's the 2nd highest selling extension ever, of course...