Check out the m5board message board E39 section , and do a search there. These topics (540i vs M5 and 2000 vs 2001) have been thoroughly discussed there. In short...get the 2001 M5.
2011 M3 Silverstone, 6MT, no sunroof
2001 M5 LeMans Blue/Silverstone
2006 330i ZSP 6MT
1996 Volvo 850R wagon