Re: getting more ram --> questions about power and compatibility
First off, you definitely don't need a new power supply for ram.
Secondly, the amount of RAM your computer can use depends on a few things.
-Motherboard: Every motherboard has a specific maximum ram amount and speed it supports. Your motherboard can go up to 8gb, so you're fine there.
-OS: If your OS is 64 bit, it can support basically any amount of RAM. If you're on 32 bit, you won't be able to use more than something like 3 gb of ram.
Now, you currently have RAM at 800 MHz. If you put in some more DDR2 ram that's clocked at 667, then I believe all of your ram will run at that speed. Which isn't such a bad thing though. If it's DDR2 800, then all of your RAM will run at that speed, which is good. You should be fine though. The fact that it's from different companies isn't recommended, but I don't think it would be a problem.
||Core 2 Duo E4600 @ 2.4 GHz (OC coming soon) || Biostar TP45HP || 4GB Kingston DDR2 667 RAM ||
Sapphire HD 4670 512mb @778/1140 || Antec Trio 650w || Maxtor 250gb 7200 RPM HDD || Lite-On DVD-RW || Black Aluminum Case||