The Athlon is a single core processor, and it has 512Kb cache, not Mb! It is also based on the older Athlon 64 architecture. Basically, The Intel E5300 will beat it easily and then some.
Interesting that on the HP site when they describe the Athlon they uniformly say 512Mb not Kb.
Anyway -- just for the record -- (1) is there an easy way to compare the 2000 MT/s bus rating to the while 800 MHz rating? and (2) is Dual Core the same as or better/worse than Core2Duo?
core2 cpus have more cache and faster FSB than pentium dual-cores, but has the same Core architecture. The core2 will be faster with apps that benefit from the larger cache, like wise with the FSB.