Solved: maximum ram for this and a HP dc7800

Hi all, my specs

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows XP Professional, Service Pack 3, 32 bit
Processor: AMD Athlon(tm) 64 X2 Dual Core Processor 4200+, x86 Family 15 Model 75 Stepping 2
Processor Count: 2
RAM: 3071 Mb
Graphics Card: NVIDIA GeForce 8500 GT, 1024 Mb
Hard Drives: C: Total - 238464 MB, Free - 149397 MB;
Motherboard: , ALiveNF6G-DVI
Antivirus: McAfee Anti-Virus and Anti-Spyware, Updated: Yes, On-Demand Scanner: Enabled

Does anyone know what the maximum ram can be run on this machine?, currently I have 2 sticks of 2GB (though strangly, the above ram only shows 3071 Mb).

I also have just bought for my son a sff desktop a HP dc7800 refurbished, it has a new hard drive etc running windows 7 and importantly it has what they claim in new memory, 4 sticks of 512 though I am unsure what it is (PC2 5300?- i think) I was wondering if anyone new what it would be (DDR2 - DDR3) and again what would be the maximum it runs, in the event I want to boost it (providing it is able take a 1GB stick being a sff machine - 2 slots are reasonable clear above if the sticks are taller - 2 are to close the the power unit).

thanking you in advance
phil