Hey can someone tell me which is better (and why):

Using 4GB (4 x 1GB) or 3GB (2 x 1GB and 2 x 512MB)?

I am running Vista32 and know that the 32bit OS won't be able to address all of the 4GB.

Is there any advantage to having homogeneous sticks in the dimms or does the mixing of 1GB and 512MB have no effect? Obviously sticking with pairs so that it will work in dual channel mode.

Because the full 4GB will not be usable, is there a much of a difference between 3GB and the 3+GB that I would have if I put 4 in? (My video card is a 8800GTS-320, because I know that the part of the memory that is not addressed is due to addressing other devices, maybe the size of my video-ram is important.)

I know that some Motherboards have problems with all four slots filled so 2 x 2GB is an option, but then I lose the 2GB that I already have. Plus is it not true that in general denser sticks have higher latencies (ie 2GB vs 1GB sticks)?

I currently have:
AMD X2 5600+
2 x 1GB 4-3-5-24
8800GTS-320
ABIT Mobo (not sure which one lol)
1TB jbod
All running at stock speeds most of the time

Thanks for the help!!!

Yes, that 320mb of video ram will eat into 32bit os's 4gb limit. No, there is no disadvantage to 2x1gb + 2x512mb. They will still run in dual channel. Although different size sticks tend to come with different timing and voltage, which is not ideal.

You should really just get the 4gb in even, identical ram, since the cost of 1gb difference is only around $20 anyway. It's easier and problem free.

there is a way to tweak 32 bit systems into recognise 4gb of ram. chech out the msdn site you should find it in there

You cannot tweak vista into doing that, Microsoft made sure of that.

Lol, it's a physical limit of 32bit os, microsoft cannot help you.

Don't lol. BlackKnight7891 touched the subject. It is called PAE. Microsoft has just crippled its use in vista and xp.