Hello to all,
I began riding in the middle of June 2005, loved trail riding, bought a GF Marlin hardtail, added BB7 discs, thudbuster, bought full springy Jamis XLT and now use Marlin on the road when trails are wet. I added Michelin 1.50" city tires and run 75 psi and have now figured out that I really like road riding and I really like my Marlin. I need some help with a couple of problems, one is I want 700C wheels and tires, the second is I want a carbon fiber rigid fork to replace the Manitou 4" travel fork. How do I do this? Any help would certainly be appreciated. I see a lot of forks on ebay for sale under a $100.00 but not many 700C wheels that accept discs. Should I return to rim brakes? What to use on the rear if I do? It seems too confusing and I should probably just buy a road bike (flat bar) and get on with it but I really like this Marlin and I really hate to do away with a bike that I have $900.00 invested in. Any thoughts, please?

but I can be done.

Ok, you wat a full carbon fork? Nasbar has one usally them or other spots. If you want 700c wheels then get a Cyclocross Fork. Now only $139!
http://www.nashbar.com/profile.cfm?category=86&subcategory=1182&brand=&sku=12387&storetype=&estoreid=&pagename=Shop%20by%20Subcat%3A%20Road%20Forks

Now get a 700c Cyclocross disc wheels. Every few months Nashbar has Deore/Mavic CXP33 135mm Disc wheels. Usally $179-199
Get a 12-25 road cassette!

Or have someone buid you a cheap pair or try ebay.

Now depending on your FD, you can run a 48T big ring. Or if you FD is Bottom pull, get a Road FD and some cheap road cranks and a 108mm BB and wolla!

Now this adds maybe too much of a cost. But for $450 you can get the wheels, tires and fork. Just use your MTB cassette to save money.

Now for $200-300 more you can just get a road bike. Or if you don't mind 8-speed a SCOTT Speedster S60 Flat-Bar roadie for under $500!

http://www.nytro.com/Scott_2006_Speedster_S60_Complete_Bike_p/sct06s60.htm

Just ask for the FB version, but I reccomend drop if you go this way.