Depends on the ultra 5 really. There are many ultra 5's that are years old and still kicking. I don't have any x86 based machines that are over two years in age. Now, when you start talking about the ultra 10's (SCSI, 4MB Cache Sparc II's) or the Ultra 60's, I'd like to see a linux machine that could outperform them. The Blade 100 is a good workstation, you'd be hard pressed to find another true 64-bit workstation in that price range. Does it do everything the blade 1000 does? Hell no, but it's at 1/6 the cost and completely binary compatible. It has it's place in the market and if you don't know what you would do with it then you don't need it =)
Rowcroft