The "3500" is only a comparison rating. Your 3500's performance is comparable to a 3500Mhz Pentium 4.
AMD's apparently can do more work on a clock cycle. Clock speed doesn't always give you a clear view on how fast a CPU is. For example, a 1GHz Via C3 processor can be slower than a Pentium 3 600Mhz processor.
anyway:
3000+ = 1.8GHZ
3200+ = 2.0GHZ
3500+ = 2.2GHZ
3700+ = 2.2GHZ, with double the L2 cache
3800+ = 2.4GHZ
4000+ = 2.4GHZ, with double the L2 cache
and for their dual core CPU's:
3800+ = 2.0GHZ
4200+ = 2.2GHZ
4400+ = 2.2GHZ, with double the L2 cache
4600+ = 2.4GHZ
4800+ = 2.4GHZ, with double the L2 cache
it wasnt the cpu it was just the transistor that they could get up to 500ghz. if ibm ever came up with a 500ghz cpu and sold it, we'd have to plug our comps into a dryer or stove plug!
not to mention a healthy supply of liquid nitrogen