Upgrading PC/XP

Hi,

I'm currently looking through a magazine for a new PC that is through my
work. I'm undicided between 2 PC's. They a

Fujitsu Siemens Scaleo P ix
Intel Pentium 4 Processor 640 with HT (3.20GHz,2MB L2 Cache, 800MHz FSB)
Win XP Home Edition SP2
512MB DDR DRAM
160GB (7200rpm) SATA

or

Fujitsu Siemens Scaleo P ix
Intel Pentium D 820 (2.80Ghz FSB, 2 x 1MB L2C)
Win XP Home Edition SP2
1024MB DDR DRAM
250GB (7200rpm) SATA

I guessing the 2nd one is better although I've never used a Pentium D 820. I
also have never had a Fujitsu Siemens PC.

Does anyone have any comments/advice? Should I look elswhere?

I have an advantage through my work as I can pay for it monthly @ 0%
interest and the payment is pre tax.

Many thanks,

Craig.

PS. I still plan to keep ME and probably dual boot.