Compaq EN P600 w/i820 chipset upgrade questions

Hi

A relative has been given a Compaq EN Series. The case is not
a vertical 'tower', but horizontal. The case is meant to be
placed right on top of a desk, with the monitor placed on top of it.

There is a sticker on the top-front-right hand side of the case that
reads:
Compaq END/P600/13d/4/128c US
Compaq serial NO. 6008 DH95 A134

This PC has the following specs:
i820 Chipset
600 Mhz Pentium III
(x86 Family 6 Model 8 Stepping 1 GenuineIntel ~597 Mhz)
128 MB PC800 RDRAM (with blank installed for continuity)
Disk Drive: 13GB Maxtor 91366U4
IDE Controller: Intel 82801AA Bus Master IDE Controller
Video card: Matrox Millenium G400 - English
CD-ROM: Compaq CRD-8400D
Monitor: Samtron 77V
Sound: AC'97 Driver for Intel 82801AA Controller

Upgrade Questions

MEMORY
I would like to remove the 128MB PC800 RDRAM modual and the blank
modual, and add two 256MB PC800 moduals, to give a total of 512MB
of physical memory. Does this Compaq i820 chipset motherboard
require ECC memory, or can I turn ECC off in the BIOS, and install
non-ECC RDRAM? Is the motherboard picky, or can I install any
non-ECC RDRAM? Also, if I choose to go with PC600 RDRAM, will there
be significant drop in performance compared to PC800?

BIOS
I was told by the original owner that the BIOS in this PC is not stored
in a flash ROM but on the hard drive itself. I'm not sure about this
myself. I have read about hardware diagnostics, or something to that
effect being stored on the drive in some user group postings. If I do
a zero fill on the disk, is there an easy way to restore this piece of
software?

NEWER VIDEO CARD AND INCREASED OVERALL POWER REQUIREMENTS
I have an nVidia GeForce 2 32MB (Dell), and a GeForce 3 64MB (OEM)
laying around. I was thinking of swapping the Matrox out for one of
these cards. Will the PSU handle the extra load of the Geforce 3
without reboots or lock-ups?

OS AND APPLICATIONS
The eventual goal is to run Windows XP, while being stable, and snappy.
The current Windows 2000 Pro install from Compaq has developed
some bugs, displays errors a boot, and occasional blue screens
after running for a day. Also she would like to try The Sims! 2 which
needs more memory and a video card with transform and lighting.


Many thanks in advance for a reply to any of these questions. I have
tried a few searches in Google, Google Groups, and Compaq's site, and
have gotten spotty info.

Edward Crismond