Having owned both, I would say go with the D50. It takes wonderful pictures, supports AF-D lenses, and has a flash.
The ONLY reason you should get a D1h is if your main (and only) focus is sports. The autofocus is great for fast action, but it doesn't help if you have a bad lens.
Even now, I look at the pictures I take with my D2h, compare them with the D1h and the D50. I like the look of the D50 pictures better, and am sad that I sold that so long ago.
Also -- make sure you are budgeting for batteries if you decide to go with the D1h. My battery (bought camera + battery used) lasted for about 3-500 pictures, or 4 hours, whichever came first. within a year, that battery wouldn't charge anymore. I'm in the process of building a Li-ion battery pack for it, but thats not for the faint of heart. replacement batteries can run you 40 bucks, and are a pain to deal with.
In short, stay with the D50 for now, and save money towards better lenses, or if you really must a D2h/D2hs/D300.