Well 5.5Ghz is not something possible to buy
About the graphic card, why a 9800? Try the new GTX275 excellent value for money, around 200€, and way better than the 9800.
Today you have two different good choices, concerning the CPU maker. AMD with the new Phenon X4 Quad Core CPUs, and Intel with the Core i7 (more will come, like Core i9, i5 and i3). Intel i7 is more expensive, but with more performance, and AMD has a very good performance with lower prices.
Let me just point this, Intel X58 allows
SLI and CrossfireX, but first you need to be sure if your motherboard supports it.
As I said before, and there always some misunderstand about that, the 2.4Ghz Pentium is worst than a 2.1Ghz C2D 6400, like mine, frequency isn't everything. Intel changed the CPU architecture, adding more cores, speeding the FSB, increasing cache etc creating a less consuming and more powerful CPU.
One last advise, don't buy a crappy power supply, buy PSU from makers like Corsair, Seasonic, Enermax, OCZ, PC Power&Cooling, Be Quiet, Silverstone.