ive gotten pretty seroius into mtb over the last couple of months, and my walmart bike just doesnt cut it anymore. My parents said theyd chip in 340, and the rest of the money is up to me. im thinking the max i'll put in about 150, so that puts me up to 500. Some of the ones im looking at in order of preference:

Ironhorse Warrior Disc: 500
Jamis Durango Sport SX: 500
Trek 4900: 430 (04 model, clearance)
Specialized Hardrock Sport: 340 (wouldnt have to pay for it )
Ironhorse Maverick Disc: 340
Trek 4500: 450?
im also hearing alot about the specialized rockhopper, but i havent demoed it, and v-brakes for 500 seems a little weak.

weight is also a factor...trying to stay under or very close to 30 pounds