Depends on what else you have of course (like the 5 disk RAID you're not telling us about ), but the 150watt Opus should be able to handle it. And unless you're very price-sensitive, the Opus is also generally the best solution out there.
Because I think bigger is better and I'd rather have too much than too little, I am going with the Keypower KP-DX250H.
My setup (so you can reference against yours):
P4 2.8ghz HT @ 800mhz fsb
1gb ddr400 RAM
60gig 2.5" HDD
PCI video card (maybe)
PCI-to-pcmcia adapter card with mobile internet PC card installed (maybe)
slim 24x IDE CD-ROM
usb bluetooth & usb 802.11g adapters
Unfortunately this PS is huge, so I'm going to run it as an external power supply and run the cables into my miniITX case through a hole I'll dremel or something. It also does not have a shutdown controller, so I will probably use the Micro Shutdown Controller in the mp3car store.
Thank you for your imput. I will be running 1, or maybe 2 HD in a raid format if I run 2, a dvd rom, 18 mb agp video card, 1 gb of ram, and a usb hub, Nothing else at the moment, would eventually like to get the Sirius satellite controls etc.
I would recommend against the 2nd HD, and might advise cutting down to 512MB of RAM (you're not building a workstation in your car, are you?) but I think the Opus will handle it. You might try comparing system notes with other opus users, I've seen various configurations posted in similar past threads. Also check out power calculators to get an estimate on your power needs.