Mac-nut needs advise on 4 dimm slots:quad core

[aka21stCentury]

Switch hitting. From a buggy yardsale Quicksilver to quad core. ASUS P5QSE with dual memory four slots. Just a gig is in there now. Should I go OCZ 2 stix of 4 gig hi-speed. This board is rated at 1033 you can up it to 1600 in bios timing settings haven't read the manual yet it came with or browsed the CD contents? Can't afford more but this way I can add two more stix latter.

Also its an old Antec ATX full size case. Holes in front for 5 opticals and a floppy, so I want to swap out to the new Antec Sonata at newegg 69.-- I've heard a local builder saying it's a quiet enclosure front is covered like the P182. Silentpc is saying the p182 is the quietest. Either way its 20 bucks for shipping.

500 watt 'Green' PSU is in the puter now. That's an Antec right? Is this decent enough? This Sonata case I'm considering has a 2 speed switch on the back for rear fan speed. I like that. But since I'm taking everything out. What would you PC experts do if you were broke, but don't want to do the work twice? I mean if eventually on W-7 max out to 16 gigs of high speed ram? 4-6 hard drives. Ati 1600 pro x GPU w/fan. PCI Firewire. PCI 001. And SCSI LVD as I have 10k cheetahs I could use for samples? Want to get Komplete 6.