Set up question Security Soft

I just bought a new machine a pretty decent one and will be using it as the main home computer with a lot of stuff such as documents media files and other things too. It has Windows 7 and i wonder which Security suite will not be compatible to W7 or will not be working good enough. It is 64bit i think and it has plenty of space and ram. ( at list for me 3 gigs of ram are plenty )
Can you please suggest?
I also have a spare Vista Home premium boxed version (DVD version) which i liked when i used it on my old machine. Is there a big difference between W7 and vista home premium?
I guess there are too many questions but i am not looking for many complicated answeres but some simple practical ones.
Cheers Gery

PS the computer is not yet opened

 

Windows 7 and Windows Vista for ME, feels quite the same thing
W7 is like Vista but more optimized and bug free.

Anyways, almost all major security software are compatible with Windows 7, the only problem is that some software such as HIPS or Sandboxes aren't compatible with x64, but you can always check their website.

 

Windows 7 is very fast and holding steady !
But Vista can feel the weight. There's a difference in running the game certainly