Sujet : What pc spec gives fastest excel data processing?

Hi,

My pc uses a 1.40 ghz AMD Athlon processor with 256mb ram, MSI MS-6380E 1.0 main board, 133 mhz bus clock.  The process cycle takes 110 minutes to complete - this is far too long. 
Windows task manager tells me the cpu is running at only 35% capacity - why is it not 100%?
As I am thinking of upgrading, can anyone advise me which pc features are critical to achieve fastest processing performance?

Please help.
Thanks!

I didn't find the right solution from the Internet.

References:
http://www.tek-tips.com/viewthread.cfm?qid=990033

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