Having had both a 2004 Gallardo, and my current 2008 R8, I would say without a doubt go for the Audi.
Its easier to live with, more comfortable to drive, handles better, and is a much newer design than the Gallardo, which especially on the inside is looking very dated now.
The G will end up costing you a fortune in maintenance, whilst the Audi wont.
Here is a couple of pics to help you decide
