well, as if an act of god (or the devil in my case) my mobo broke, most of the copacitors or whatever the little things sticking up from the mobo broke. in any case i need a new 1 but i don't want dell's. my other components are as follows:
1x 160GB sata Seagate Barracuda
1x x16 cd-rw/dvd player
1x AMD Athlon 64 X2 3800+ currently clocked at 2.0 GHz
2x DDR2 pc2-5300 677MHz 512 MB 240 pin DIMM RAM
2x DDR2 pc2-6400 800MHz 1 GB 240 pin DIMM RAM total ram 3 GB
1x Sapphire ATI radeon 4650 512 MB DDR2 Memory 128 bit pci-e 2.0
1x 250 watt dell power supply <---- needs to be upgraded, i know
stock everything else including cooling
i really want to keep my memory but if 2 gigs is enough its ok and I'm a mid level gamer so im going to need a pci-e 2.0 mobo
the reason im not doing the research myself is that 1. piece of mind for me and 2. proof of what can fit in our case.
More than likely, that Dell case will not fit a conventional ATX or Mini-ATX motherboard, again, i am not too sure on this one, but dell has been known to make proprietary cases that only fit motherboards offered by dell.
If it were me, i would start fresh with a new case, power supply and motherboard, the rest will fit just fine.
as for the RAM issue, what operating system are you using and is it 32-bit or 64 bit? I would just stick with 2 x 1GB of the PC2-6400 RAM and ditch/sell the PC@-5300. Motherboards tend to get a little finicky when more than 2 sticks of RAM are used especially if they're not the same RAM sticks.