EF 17-40 f/4 L or the new EF-S 17-55 f/2.8 IS.
Well, the kitlens isn't that bad as everyone shouts. If you avoid the outer ends (use it as say a 20-50) and stop it down to f/8 it's quite decent and very cheap for a wide-angle.
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EOS 5D|EOS 600|15-30|24 1.4 L|135 2 L|2x 580EX|2x CP-E3|ST-E2|2x Pocket Wizzard Plus II|IXUS 850IS|Crumpler|Manfrotto|
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