P5N-E SLI + Ultima-90, HR-05?

[CallMeJoe]

Current system specs:

Asus P5N-E SLI w/Zalman ZM-NB32 on Southbridge, stock Northbridge HS, E6300 w/Sunbeam Silent Whisper (PWM fan)
Antec Solo w/ Seasonic S12-430 PSU, YateLoon 120mm exhaust fan, 92mm intake on the HDDs
Buffalo Firestix 2 x 512MB (4-4-4-12, 2T)
Asus 7300GT 256MB Silent
Westinghouse 22" LCD
Raptor 74GB (OS & Programs)
Seagate 120GB (Storage)
Samsung SH-S162L DVD Burner

The system is quiet with a moderate overclock (375 MHz FSB, mem 1:1, 2.625 GHz processor), and is absolutely ORTHOS stable, CPU temp topping at 56C after 1+ hours. I'm looking at more RAM since DDR2 has gotten so cheap and maybe a CPU heatsink and Northbridge cooler upgrade so I could push the clock higher and still keep all my temps down.

Has anyone mounted an Ultima-90 on this board? I'd mount it pointed at the exhaust and probably use an Arctic Cooler 92mm PWM fan (FDB) on it so I could keep the speed control on the HSF.
Will the Ultima-90 fit with a HR-05 on the Northbridge? Is the HR-05 a worthwhile upgrade? Would it be worth replacing the Zalman Southbridge HS with a HR-05?
I was looking at A-DATA Vitesta 2 x 1GB DDR2-800 CAS 4 RAM, but noted in the reviews that this RAM tends to run hot. Should I look at OCZ, Crucial or Corsair instead?
Would it be worth buying some of those little MicroCool MOSFET sinks for the voltage regulators?

Any thoughts or suggestions? This is a general purpose PC (no gaming, as you can tell from my video card), but I like a quiet, fast booting, fast running system, and don't want to sacrifice stability.