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.

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Current stable:
2011 M3 Silverstone, 6MT, no sunroof
2001 M5 LeMans Blue/Silverstone
2006 330i ZSP 6MT
1996 Volvo 850R wagon