Originally posted by: Lucifer
No problem, Mhaddy2. If I were to choose a graphics card for my G5, I would choose the 9800 Pro. Though it is kind of pricey, at $249 straight from ATI, I would choose that over any other video card. The dual link DVI on the 6800 ultra DDL and the X800 isn't necessary for me. And as stated by barefeats, the 9800 pro with 128mb of VRAM easily outperformed the 9650 w/ 256mb VRAM.
A PC video card wouldn't work with a Mac. The only way I believe to get a PC video card to work with a Mac was to flash it. But I think there were only certain video cards that could be flashed. So a PC Radeon X850XT wouldn't work with your Mac.
RAM and Hard drives are all compatible. Though OS X is kind of picky with RAM, I just went to my local PC computer shop, picked up 2 128mb sticks, popped them in my Mac, and they were recognized. I also bought a 40gb hard drive from a friend for 5 bucks. He was using it in his PC. I just popped it in my Mac, and it was recognized. I just had to reformat it, since he left all his junk on it.

So yes, you can pick up RAM and hard drives from your local PC shop, and install them in your Mac.
But with CD drives, DVD-R/RW drives, etc. they are not all compatible. A friend gave me a brand new Sony DVD-R/RW drive since he owed me money. I installed it on my Mac. I put a cd in the drive, and as soon as I closed the drive, an error popped up saying the drive didn't support my OS. So I had to take it out. Most drives at a PC shop are most likely not compatible with your Mac.
Regarding the Mac mini, I owned one for about 2 weeks, but I sold it to a friend that desperatly needed a computer. It was a 1.25GHz with 512mb RAM. I actually didn't use the mini until I set it up for my friend. That thing was fast! He loves Garageband, and it runs very smooth. I was suprise on how fast that computer was. He loves it. I think the mini packs a lot of power for the price. Hell, a G5 may not even be necessary. I use a 400mhz Powermac G4, the only Mac I currently own. Reason why I didn't keep the mini is because I wanted something I can upgrade, like processor upgrades, etc. Only thing that seems to be user upgradeable in the Mini is the RAM.
And as stated before, don't buy RAM from Apple. They charge an arm and a leg for their RAM.
If you really need the power, either get the G5, or like others said, build a really fast PC. Just remember to get AT LEAST 512mb of RAM. OS X and Windows flies with a lot of RAM.
If I had to choose between building a PC or purchasing a G5, personally, I would choose the G5.

But that's just me.