Dual Xeon 800, Win2K and Quake 3

Hi!
I have the following problem(s) and question(s):

The setup:
Dual Intel Pentium III Xeon, 800Mhz, 133Mhz FSB, 256kb Cache.
Supermicro S2DM3
512MB RAM @ 100Mhz
IBM UW HDD
V5 5500, Driver ver. 1.04 (newest)

Win2K, SP1
Quake3, ver. 1.27

Problems:
The computer is very, very slow, or is it?
The fps (~60 @1024, no details) I get in Quake are lower than a K7-750 (classic) with a Geforce256.
If I try to run Quake with SMP, it crashes on startup.

The following questions arise:
1. Is it slow, or is it not?
2. Is Quake3 SMP crashing on Win2K a known problem?
3. What is the actual difference between a P-III and a Xeon now that they both have the cache on-die and it has the same size in single or dual configuration?
If there is no difference, who the heck needs them anyway?
4. How hot are they allowed to get? I haven't found any information on the Intel website?

Apart from that, has anybody tried to overclock them?

Thanks for any help or ideas!

true but it should perform bad

I meant to say it shouldn't perform bad. I think the only difference is that it has more chache. The xeon are meant for server or workstations as the extra cache is needed for high end operations that require to store a lot of information for processing. Quake 3 hardly gets a performance boost because it wasn't created from the ground up for dual cpu. It was more of a test for them to see what they could get from it which turned out not to be much. It is most reliant on the video card.