No warlord, 5870m is faster than 280m, up to 25% faster indeed, look at links provided in first post, compare benches of 5870 and 280m.
5870 is only single mobile gpu at 19xx resolution I would buy right as it will play at that resolution for a while to come.
Only sli beats it, and I do not see 360 aka gts240 playing 19xx well or for long!