sparker366:
Always advisable to buy the same ram when adding more. If you don't there could very well be voltage differences and the cas needs to be the same as does the timings. This could and most like cause instability in the system
Why 6gb's of ram? Are you just itching to fill all the slots
Dump the 2gbs and just get a single 2x2gb kit Or just buy another 2gb kit of what you got. You will need a 64bit os to see anything over 3.5gbs anyways so if you don't have that then getting another 4gbs really is a waste.
As fro gaming it may or may not make a difference load times may be better as more of a level can be loaded into ram less swapping out to the hard drive is needed.
Well-said, sparker. A 64-bit processor is a must otherwise you're wasting your moeny. Some people might think 6gb is overkill, but who knows with Vista Ultimate 64? Also, if you've got a crappy processor, I'd look into upgrading that first. It'll help boost your system's speed. I've got a Q6600 with 2x1gb of OCZ DDR2-800 RAM that runs great with very few/rare problems.
Intel Q6600
MSI P6N 650i
2x1gb OCZ DDR2 800 RAM
1xeVGA 8600GT, 1xXFX 8600GT
1x112gb Samsung, 1x320gb WD, 1x160gb WD
1xDVD/CD RW drive
PC Power & Cooling 750W PSU
Creative X-Fi Fatal1ty Champion sound card
Logitech Z-560 THX 4.1 speakers
NZXT Zero case (fans: 7x120mm, 1x80mm)
Logitech G5 laser gaming mouse