finally, Intel has a 64-bit Xeon (Nocona 3.6G) can go head-to-head with Opteron on high-end database applications:
Nocona 3.6 pulls slightly ahead of OP250 on SQL read/write, and slight less on enterprise application (order-entry and stored procedure).
keep in mind that they are compared between:
2x $970 Nocana 3.6G with 4G DDR2
-400 ECC reg ($1400) = $3340
2x $850 OP250 with 4G DDR-400 ECC reg. ($1000) = $2700
opteron is still about 25% better in term of performance/cost ratio.