Quote from Dgatwood:
"Ignoring the fact that it is based on older converter technology, the main reason I'd recommend against the MobilePre is that the phantom supply voltage is inadequate. That's an unfortunate side effect of the interface being solely powered by the USB port, as far as I can tell."
I don't think so. It's more a function of bad (and cheap) engineering. There are plenty of USB powered units that can deliver pretty damn close to a real 48v. Zoom offers a 24V/48V option, to save juice when using less critical mics. The C2000b, for instance, does fine with 16V, by spec, but the KM184 wants 48V or else. Line 6 UX-2 does fine. The Mobilepre is really just an obsolete, poorly designed, bottomfeeder interface.
Anyway, for that $500 budget, I'd probably buy
a Line 6 UX-2 (on sale)
http://www.8thstreet.com/product.asp?ProductCode=60669&Category=Audio_Interfaces
and a B.L.U.E. Bluebird:
http://www.8thstreet.com/product.asp?ProductCode=41078&Category=Microphones
If you want to save some money for cables, headphones, etc. (You will need monitors but they are not really in the current budget), The V67 recommended above is not a bad choice:
http://www.8thstreet.com/product.asp?ProductCode=6458&Category=Microphones
How do you hook it up to the computer? By USB. The problem with USB mics is not that they use USB. The problem is that their Analog-to-Digital converters suck, and their preamps suck. It is worth noting that this probably doesn't apply quite so much to a Neumann Solution D- but that's an $8,000 or so digital mic, and I'm thinking that $7,900 and a few looney German engineers could improve the platform a bit.
The UX-2 comes with Ableton and Reason audio processing software, but many here swear by Reaper, which is dirt cheap on line.
Also note that there are very small mic to USB adaptors. Unfortunately, the cheaper ones don't give you a headphone jack like some USB mics do. Anyway, using an adaptor is a better choice than a USB mic when you want to go direct to USB, when you don't need real good audio quality (say remote podcasting). You can use the adaptor with *any* mic, so you are not saddled with a mic that can only plug into a computer, and has poor quality electronic components built in. Note also that the little USB adaptors don't have preamps or A-D conversion that's any better than the average USB mic, but at least, *you can disconnect them* Example:
http://www.8thstreet.com/product.asp?ProductCode=44712&Category=Audio_Interfaces
Best of luck-Richie