Mountain Biking - urban bike reccomendations

I'm building up an urban/dirt jumping bike and was wondering if anyone had any suggestions? My plans are as follows:
Frame: Da bomb CR8 (deffinate)
Fork: Marzocchi DJ3 (deffinate)
Drive train: sram x.7 with raceface evolve dh cranks
Disc Brakes: Hayes hfx-9 or maguras?
Wheels: alex extreme fr/ jumping rims, xt IS disc hubs, 14g 3 cross spokes, brass nipples
Tires: 2.35 or 2.5's? I dont know on this one, and which ones? I was thinking kenda tomac nevegal dh?
Tubes: any difference between dh tubes other than thickness?
Others: for the seatpost, stem, bar, seat, grips, etc anything I can afford

These are my thoughts as of now, but Im just breaking into the sport so Id like to know if I have a good set up. Thanks!

Keep the rubber side down

i'd suggest something other than the hayes nines. they're problematic. everyone i know that has them has experienced some type of problem or another... i've got a set and i'm experiencing what many others are: loose adjustment screw that makes the brakes feel really spongy. (i still gotta get me some locktite to fix that problem).

one of the guys i ride with occassionally has also had the little plug on the master cylinder pop out during a run, spilling his brake fluid everywhere - and that's never fun.

so, if you can afford the hfx mags, then go for those instead.

which maguras are you thinking of getting? maguras are nice brakes... better modulation than hayes, but they're usually more expensive. i've got a set of julies on my tassajara and they're great. no real problems except for the rear screaming like a banshee everytime i'd brake on decents.

good luck with your build. and post some pictures when you're done. ;)

Thanks for your help, I ended up ordering shimano 525, (cheapest what can you do?) I don't have the parts yet but will post when Im done