The truth is...it doesn't really matter which ones as they should all interoperate
The 11b ones operate at 11 Mega bits per second (or allow for about 1.2 Megabytes of data). 11g operate at 54 Mega Bits (or about 6MB). Some of the faster ones use several channels at once to double/treble the speed.
Real advantage of 11g over b is the increased range.
I use: a D-Link 654 router (bought in the US for about £25), 2 Microsoft something or other 11g PCI cards, 1 Belkin 11g PCI card, 1 D-Link USB wireless adaptor (11b).
From ebuyer the codes: 64620 (router) and two of 45622 should set you back about £85 plus postage.