Brother Richard said:
I've got some sympathy for this approach. If your DM allows it, the warlock is a much simpler solution.
Otherwise Elf fighter all the way for damage - although survivability (hit points and saves) isn't that startling. Using point buy (if <32), take a 15 Dex to start, +2 racial to 17, and then bump to 18 Dex at 4th.
Feats would be Point Blank Shot, Precise Shot, Rapid Shot, Sharp Shooting (Complete Warrior to reduce your penalties for firing through cover, ie your buddies engaging some enemy), Wpn Focus/Specialisation, Ranged Weapon Mastery (PHBII), Manyshot, Improved Precise Shot, and Greater Manyshot (Complete Psionics? It's in the SRD under the Psionics section at any rate). Eventually Greater Wpn Focus/Specialisation and a few other feats from PHBII would fill the few remaining feat slots.
As for a bow, it should be a magical composite bow (with the appropriate strength rating) and (as was said peviously) should have bonus abilities such as frost/shock/holy etc. See if the arcane or divine caster will Greater Magic Weapon your arrows at later levels.
Need Efficient Quiver to carry all the arrows you need, and maybe some decent ranks in Craft (bowmaking) to make your own arrows in your downtime when away from cities.
A Glove of Storing wouldn't be a bad idea to keep the bow out of harms way.
Enlarge Person would also increase your damage, but not worth taking a level of Wiz for.