Intel Xeon old/new differences

It would really depend on the price, but I have worked with the Compaq DL 580 recently, a dual 1400Mhz Xeon, and it is quite fast. I compared the responsiveness with another client that has Quad PIII Xeon 733, and well, I'd go with the dual P4 Xeons any day. Cache does matter, but only if you compare same speed CPU's. 256k L2 at 1400Mhz and 512k L3 at 400Mhz is better than 2MB L2 at 900Mhz in my opinion.
If price is not a problem, I would definitely go with the P4 Xeons. The 4 processors with Hyperthreading should help out at least 10% to 20% (if not more) with DB operations, with regards to a comparable system that doesn't use Hyperthreading.

Well, I know what happened in the PC market. The PIII 1000EB was rougly the same performance as the P4 1.4GHz. These are the same cores used for the Xeon 900 and the Xeon 1400.

Now in the PC market, the 900 moderately underperformed the 933 simply because it ran at a slower bus speed. The PIII Xeon has the same limitation of the PIII 900, a 100MHz bus.

So the 900 Xeon should have about 15% lower performance than the 1400 Xeon, if they had the same amount of cache. But because the 900 2MB has 8x as much cache as the 1400, it will probably perform slightly better in such applications that make good use of cache.

I wouldn't upgrade.

<font color=blue>You're posting in a forum with class. It may be third class, but it's still class!</font color=blue>