God, it sounds like quite a few people have had similar symptoms, to what happened to me about 3 weeks ago.
Anyway, I didn't download it, I bought a dvd. It installed OK, but when I booted it, it would get as far as started X etc and no further. It would drop me into a system command input.
In my case, an aquaintence (who also happens to be a deb developer), came round and configured it all for me.
He confirmed a few things.
I had got the woody dvd. OK
My graphics card is an nvidia geforce 4 m420 (not exactly cutting edge, but reasonably current). OK
It transpires that nvidia drivers do work, but woody only seemed to have stuff for cards upto and including geforce 2 - The nvidia site has got drivers that work, but they aren't "gpl'd" so not included with the debian disc. OK
It also transpires that the nvidia drivers aren't supported by the 2.2.xx default kernel that installed with the woody, but they work with 2.4.xx kernels (or so I understand).
I ended up having to work out how to use "Lynx", the text only browser (which was installed by default) then going to the nvidia site and getting the driver (though I didn't know what to do next). When Steve came round, he checked over what I had done, and the first thing he did was to do a dist upgrade with apt-get (to sarge, which installed a 2.4.xx kernel by default), then he unpacked the nvidia driver and installed that, then he did some configuration of X (xf86config I think, It was all getting rather over my head and I could only watch!
This got it all up and running (basically), because it took me ages to work out how to get it to play audio disc's and get system sounds working. Which I did eventually manage.
While all this was going on, I decided to check out knoppix (another aquaintance from the LUG had given me a copy of 3.1). Knowing that knoppix is debian based, I ran it from the disc, and it recognised and configured all my hardware and gave me a few clues about the sound problem (i.e. that I needed the "ide-scsi" module to use the cdrw that I've got, and some other bits and bobs).
What it did do, was show me a better view graphically, than what I had managed to do myself, show me an installer that worked seemed a lot better than the manual stuff that I had managed to work out, and a mega easy way to getting my "network" configred, and the package selection with knoppix is better than what I knew about i.e. I was able to do nearly all the stuff that I can do with my mandrake install.
I persevered with normal debian for a while, then eventually I did a "hard disc install" of knoppix over the top of the normal debian sarge - which basically gives you a normal debian install with a few differences. I'm very pleased with it.
So I don't know if any of this will be of any help, but it may point you in the right direction (I know that my post may be a little too general for what you need to do!), but hopefully it helps
p.s. the only problem that I have actually had, is getting the knoppix/debian to boot from my hard drive, but that's because I "multi-boot" with XP and mandrake as well - and it's the mandrake install of lilo that I use.