Mountain Biking - wanna get a hard-tail...

i wanna get rid of my bmx. i have a mosh lux 4 star. i rode my friends specialized p2 today with 24's on it and it was pretty cool but felt a little short for me. then i rode his other hard-tail thats all custom built with 26's and i was like =O i want!
he said i should get a kona or build something with a soul cycles frame. what do you guys think would be good for me? i'm 5'10" or 11" and about 135-140 pounds.
gonna be doing some dirt jumps. wanna jump stairs and stuff like that though too.
i want a single speed (or i can get my friend to convert it for me).
looking to spend maybe like around 600$ =/

P2 does feel short compared to matching bikes.
Soul cycles is ok, but it isn't built for SS properly (no horizontal dropouts) which makes it a royal pain imo.
Kona does make frames that might work for you, but I am not sure if they do a SS...Would have to get it converted

Well to convert to single speed. You can always buy a bunch of spacers, and in the place of 8 of those 9 gears put in a cog. THats what one guy at my shop likes.

Why not get the P1?

my friend said he'll sell me his new frame for like 150$. i forgot what kind it is but it feels really good. He said he could get me a good price on some dirt jumper 3 forks since he works at a bike shop. and all the other stuff i'll need.

If you havent looked at it already, the freeride hardtail sticky at the top of this forum has a pretty comprehensive list of bikes suited to the type of riding you're interested in.

http://www.bikeforums.net/showthread.php?t=79185

Just in case the deal with your friend doesn't work out or something.

Take a look at the Kona Unit. I was at my LBS the other day and they had one for around $550. I would have picked it up but it was too small for me. Single cog 34x17.

The unit is more xc/road oriented, isn't it?

The specialized P1 is perfect for what he's doing. The p1 cromoly is nice, except it has a 24" wheel in the back and 26" front... might handle weird.