I need a patch here

If you mean more than 4gb of ram then it is not possible with a 64bit os

if you mean the PAE patch

then here it is

how stable or if it works for you is another issue

http://wj32.wordpress.com/2011/02/23/pae-patch-updated-...

so i have to upgarde on 64 bit ?

If it's more than 4gb of ram you want then yes.

But it's not an upgrade. You have to reinstall.

Doesn't PAE break the NX bit?
- Data Execution Protection is more important.
- No Win32 (std) process can allocate more than 2GB RAM anyway
- Yes the other 2GB will be used, as you'll be running 80 or so processes (not processors) 'at once', plus the kernel.

32-bit Windows has smaller pointers, so for most apps (85%+) it's faster and uses less memory.

if i install only 4gb ram can i run 32 bit ?

You can or you could use 64 bit and get your whole ram  

ok i will go for ultimate 64 bit ,by the way is it good for gaming ?

Yes. It is superior in pretty much every way.

I wouldn't spend the extra money on Ultimate for gaming (although I sense a torrent initializing...).