My computer can have a max of 8 gigs of ram with 4 slots of 2gigs each. I'm lost on the whole dual channel / quad channel memory. If my system is older and handles dual channel memory does that mean I buy two dual channel kits or does one quad channel kit work?

I just did my taxes and I'm getting a good return so I want to upgrade my system after I change over the operating system to windows 7 pro 64.

To be brief, yes. You can buy just one stick of RAM and as long they run the same volts, and memory frequency and timings it doesnt matter if its octa channel. RAM is RAM the channel kits are just names because those two slots work in conjunction with each other, hence dual channel but you can run with only one stick or both. So just because you have dual channel does not mean you need to fill up all the ports for it to work. You could just take out one of the 2 gigs and still be ok. Just make sure if you do get new RAM make suer teh timings and frequencies are the same.

The thing about those kits is that the sticks included are paired, essentially the memory is designed the same and has all of those similarities that bleep mentioned and buying kits is recommended for those reasons. If you get a 4-stick kit, you'll be fine.

Buy the highest frequency ram you can without getting too expensive.The higher clocked sticks can always go down but you cant always go up.Also higher clocks will let you run tighter timings if you run them slower.Read the reviews for the ram you can usually find out if they will run the timings advertised or not,alot wont.If your board calls for ddr3 1600 buy 2000 and let it run at 1600 with tight timings if your not over clocking,if you are then all the better.The price difference is not bad for the performance you get.

Also, a lot of times, the higher frequency RAM is actually cheaper because it's the stuff being made the most.