i really don't know much about linux, but considering the community things usually happen a little faster there, so it would not surprise me at all if it's built better for the architecture. however, FreeBSD is now supporting a full seperate release version as "tier 1" for the chip, so i imagine the support is at least fairly decent. i wouldn't imagine they'd name a release version and have it suck total balls.
if my memory serves me correctly, amd and ibm were somewhat of bedfellows in producing the opteron chip. i believe in the basic architecture the g5 and opteron are very similar, although the amd chip seems a little more refined. it can, for example, support 2x the memory of the g5 i believe. i dunno about the hypertransport issues, but that may also be an improvement.
however, independant tests are actually that, and in most situations it seems that the amd chip does have an edge over intel, even with the EE's l3 cache. only in programs that really use that (which is fairly limited), and games built on the quake 3 engine does the p4 come ahead. so, even though there really isn't a lot of support out yet for the 64bit architecture, it's still performing admirably in that area.
just something to think about.
