Legal advice: General partnerships, $, IP, and going it alone

I’m in this position:

Someone found me through an ad on craigslist, and eventually introduced me to their idea, which basically amounts to, “it’d be awesome if you took algorithm X and made it run really fast by putting it on a GPU.” He offered to be partners in this venture.

Now I happen to have some experience programming things on GPUs. I took a look at the algorithm, its application, the competitors in the field, and saw that it was a good idea. I’ve been working on implementing this thing the last several weeks and with good results.

Now, I don’t mind having a partner. And although I don’t know this person long enough, they’d probably not be a bad one. But what are my options for going it alone? Do I owe something massive for this person’s quote-unquote intellectual property? I mean it was a good suggestion but not all that deep. Then again with what passes for a patent these days… From the teeny bit of law books I’ve read, I might have also automatically entered into a general partnership?

What complicates things is that to move forward it’d be good to have a performance test rig made up of three servers. This other person was more than eager to put up the money. Now I’m supposing accepting this offer (not the hardware itself, but I guess him buying it then lending it to me) would put me further in the “break up and you’ll owe him 50% as if you’ve had three kids” territory?

Is it time for a prenup? Or have I got things wrong?

No lawyer on these boards is going to offer you specific advice on an actual situation. What you are going to get is at best very general comments (if that) from people who do know what they are talking about, specific advice from people who don’t know what they are talking about, and suggestions as to sources of information (like this one):

If there’s no money to be made out of this, then it doesn’t matter. If there is, then go see a lawyer.

Err, i know i know. I welcome general comments. I just need to get a sense of things, and then I’ll go to a lawyer if I’m treading on something thin. I probably shouldn’t have said “legal advice.” That has a formal meaning, doesn’t it?