In reply to lynsey.a:
Don't get Tri Cams. They're great, but really rather specialised bits of kit. Certainly no substitute for cams/hexes, which should make up the back bone of everyone's rack.
I'd get three cams and a gold hex (Rocentric 7 and Torque 3).
Which models you get and in what sizes is up to, personal preference, budget and where you climb.
If you generally climb on mountain rock then sizes 0.5, 1.5 and 2.5 would probably be a great starting point.
If you climb more on Gritstone or granite then you'd probably be better off with either sizes 1, 2 and 3. Or maybe even 1.5, 2.5 and 3.5.
NB - I'm working on standard friend/4cu sizes here.
Camalots and Dragon Cams are fantastic bits of kit, but are loads more expensive than DMM 4CUs. You could probably get 4/5 DMM 4cus for the same price.
The Climber's Shop in Ambleside has 25% off BD gear at moment, offering huge savings on Camalots:
http://www.climbers-shop.com/256658/products/Black_Diamond_C4_Camalots.aspx
Oh and don't discount Wild Country Technical Friends.
At the end of day if you buy a cams from any of the big four manufacturers (BD, DMM, WC and Metolius) you won't be disappointed and none of them will hold you back.
HTH