Help.

I have a workbook containing 7 worksheets. One of which connect to an
external data feed through a vendor's dll which will refresh every 5 seconds.
The rest sheets refers this sheet's data and using tailor functions.
Previously, the users open four such workbooks each containing 3000 records
in a Windows2000 computer installed with Office2K only consume up to 70% CPU
resources. After we move those workbooks to WindowsXP installed with
Office2003, just one spreadsheet consume 60% of CPU resources.

We set all the vendor's dll as object in VBA and calls out as property. I
have already turn off all screen update before run the functions and turn on
all updates after functions finished calculations.

The configuration of the Windows2K a Platium IV 2.8CPUx2, 2G RAM 100M
network
The configuration of the WindowsXP are" Xeon E6000 CPUx2, 2G RAM, 1G network

Can anybody helps me?