Usually I would never answer a question like this because if you go to the Apple site the answer if right in front of you. I'm in a good mood though, so here's the answer:
1.25GHz Mac mini: Combo Drive (DVD-ROM/CD-RW)
1.42GHz Mac mini: Combo Drive (DVD-ROM/CD-RW)
SuperDrive Mac mini: SuperDrive (DVD±R/CD-RW)
I found out that my Mini has a Matshita UJ-835F Superdrive, and it's absolute rubbish.
Using Toast 6, it constantly creates coasters, because underrun protection isn't possible when burning DVDs. It's total BS.
I now have to go buy a Pioneer drive that has underrun protection for burning DVDs.
Apple must have been desperate... I can't believe they used this matshitty drive.
So buy your Mini with "cheapest CD drive", get internal bluetooth/airport, and minimum ram (upgrade it yourself to 1gig, as even 512MB isn't great with tiger).
The solution is that I have to pay US$120 for a Pioneer DVD Burner. And I'm gonna smash my matshita drive into thousands of little pieces, because if I sold it, I'd be passing on my nightmares, and my conscience couldn't stand passing on that much pain to another human being.
Using an external Bluetooth USB dongle is also not a great solution, and is risky when compared to the internal option.
I've already checked that page (it's for the B not the C). The only way you are going to get 8x or DL is to get different firmware onto the drive somehow. The drive as shipped will not burn at more than 4x.
To find out I put an 8x DVD-R in, dragged a file onto it and clicked burn in the Finder. The window it brings up lets you choose the speed as well as cancel the burn (before it starts). It would only allow burning at 4x.
Unfortunately the XK8 is dead. If you do a bit of fishing around in the Community Forums from 4-6 months ago you can find out how. I've got an MX-5 for now (until I can afford to insure and XKR).
I have a mac mini with a combo drive.. and I think I've inserted like 2 CD's into it since I bought it. I've got an external DVD burner that I got with my iBook for Christmas so I decided to not buy the SuperDrive option. I love this machine though.. it's great. I've got a ton of blank DVDs and CDs laying around. I only use CD's in my mom's car because I have an FM transmitter for my iPod in my car.
Also, the internal BT is great.. finds my mouse and keyboard right away. The dongle I had on my iBook would take forever to find them.