Marvell, never ever.
nForce would be competitive with Intel but consumes and heats a lot.
G means integrated graphics: only if you don't play.
The 48 is OLDER (slower process) than the 43 and 45 and won't overclock as well - I feel it important with an E8400.
My P45 (+E8600) runs at Fsb=1600 and ram=1100 at stock voltages, nice.
The 45 can split its Pci-E, the 43 can't, only difference. And some P45 mobo don't.
BEWARE only some southbridge (=ICH) can access disks exceeding 2TB:
ich9r, ich9do, ich10r, ichdo.