That should be a nice setup. I don't know if that particular board is overclockable, but the predecessor RS480-M board wasn't that great stock, hitting mostly about 220-230MHz system bus.
Hardforum guy made a modded BIOS for the original RS480-M that some people have gotten to work with overclocks well over 250MHz system bus, so there's hope.
Other differences between the two boards... the RS482-M has the new revision of the chipset that supposedly runs cooler. It also has optional 1394A (Firewire 800) instead of the original's standard 1394.
The USB and HDD controller on the Southbridge is questionable. ATI Southbridges have never performed well. Using SATA may be the limiting factor in the lousy overclocks on these particular boards.
Still, it sounds like an interesting board and is pretty much free with the CPU.