ok, since you might not yet know the additional info we need about how the motherboard will be used, what size it needs to be, what bells & whistles as well as price, I guess you are just starting out.
My suggestion is look at the Nforce 2 400 or Nforce 2 ultra 400 chipset motherboards. Nforce 2 is the best performing chipset for the 32 bit amd. the standard 400 has the single memory bus architecture we have known since forever, and is a great performer for cheap.
the Ultra 400 uses dual bus memory ( theoretically doubles the memory bus - increases performance in real world by like 5%) and is higher end. Both should overclock with a passion.
as for the southbridge - if you want excellent onboard sound go high end board with a MCP-T southbridge chip - (think near audigy 2 quality with benefits)
My suggestion - high end look abit, asus, dfi lanparty 2, epox.
mid - lower end - biostar, Fic, etc.
Avoid the ECS, PC Chips and some AsRock boards. (ecs & pc chips are iffy quality wise and may not have overclockability..) Shuttle I would personally avoid since they are made by ECS. HOWEVER, many people swear by them (and it could be that ECS makes a better quality board for them than their own brand... I find it strange to dork your own brand while being able to produce better boards... but that seems to be the ECS philosophy...)
In general nforce 2 400/ultra 400 is the best choice hands down to get.
Hope this helps. give us a bit more info and trust me, these [H]ardforum posters will give you a great series of boards to choose from . . .