That was basicly a downgrade you did there but here ia the supported cpu list yours is way slow.
http://h18004.www1.hp.com/products/quickspecs/12863_div/12863_div.HTML
Intel Core 2 Duo Processors:
Intel Core 2 Duo E7300 Processor (2.66-GHz, 3 MB L2 cache, 1066-Mhz FSB)
Intel Core 2 Duo E7400 Processor (2.80-GHz, 3 MB L2 cache, 1066-Mhz FSB)
Intel Core 2 Duo E7500 Processor (2.93-GHz, 3 MB L2 cache, 1066-Mhz FSB)
Intel Core 2 Duo E7600 Processor (3.06-GHz, 3 MB L2 cache, 1066-Mhz FSB)
Intel Core 2 Duo E8300 Processor (2.83-GHz, 6 MB L2 cache, 1333-MHz FSB)
Intel Core 2 Duo E8400 Processor (3.0-GHz, 6 MB L2 cache, 1333-MHz FSB)
Intel Core 2 Duo E8500 Processor (3.16-GHz, 6 MB L2 cache,1333-MHz FSB)
Intel Core 2 Duo E8600 Processor (3.33-GHz, 6 MB L2 cache,1333-MHz FSB)
Intel Core 2 Quad Processors:
Intel Core 2 Quad Q6700 Processor (2.66-GHz, 8 MB L2 cache, 1066-MHz FSB)
Intel Core 2 Quad Q8200 Processor (2.33-GHz, 4 MB L2 cache, 1333-MHz FSB)
Intel Core 2 Quad Q8300 Processor (2.50-GHz, 4 MB L2 cache, 1333-MHz FSB)
Intel Core 2 Quad Q8400 Processor (2.66-GHz, 4 MB L2 cache, 1333-MHz FSB)
Intel Core 2 Quad Q9300 Processor (2.50-GHz, 6 MB L2 cache, 1333-MHz FSB)
Intel Core 2 Quad Q9400 Processor (2.66-GHz, 6 MB L2 cache, 1333-MHz FSB)
Intel Core 2 Quad Q9650 Processor (3.0-GHz, 12 MB L2 cache, 1333-MHz FSB)