I've only got one example and there are lots of variables. I was running a pretty active site with 4 front end webservers and 1 NT database box with 2x2.5 Xeons and 2gig memory . We decided to switch to a 4x1.25 Sparc with 16gig and fibre channel (Apple xRaid). Due to the budget, the upgrade path included switching to a 2x1.0 Sparc 4gig memory box. The reason for the upgrade was the NT box needed more disk, it was too slow at times and it's 2gig memory limits were a problem.
The upgrade required running on the 2 processor Sparc box for 3 months and I was concerned that this would be a problem. Much to my surprise it turned out to be faster and more stable than the NT box.
As I said there are lots of variables. The Sparc box had more memory but being 64bit it could make use of it. It also had the xRaid drive verses 12 10k scsi drives. I also suspect that Solaris is more stable than NT. Finally it was Oracle 8i on NT vs Oracle 9i on Solaris.
Perhaps this is more a 64 vs 32 bit difference. I'm sure on 32bit arithmatic an x86 would run circles around Sparc, but if you've got a 4gig dataset and the x86 has disk access and the Sparc does not, the Sparc will win every time. That combined with the fact I can buy a 1u new Sparc box for $999 leads me to believe that the price/performance is better for this kind of application at this time, although my guess is when the AMD 64bit chip becomes well supported this will no longer be the case.
