Try and find some reviews with across-the-board comparisons with other coolers. Since the Zalman 7000 and 7700 are so (darn) popular, they are often included in good reviews.
There is a new make/model someone e-mailed me -- something called an "arctic Freezer". I found reviews comparing to Zalman 7000 and TR XP90 or XP120, and the ThermalRight XP series still trumps all, even if by only a couple degrees C on the "load" end -- which is what is most important.
As to the XP120 and the P4C800 Asus boards. Yes, you have to bend the capacitors to make it fit, but they wouldn't suggest doing that if there was significant reason to worry. I've bent the connecting wires soldered to the mobo for these capacitors by accident on more than one mobo, and it really shouldn't be a problem. Still, the uncertainty could paralyze you. I was luckier with my P4P800.
For the Prescott 3.2E, you really want an effective and efficient air-cooling solution, although many (and here) note that your temps are satisfactory with the stock cooler. But I've seen posts here and there that the temps can be brought down to the 42 to 47C range at full load, and it always involves a cooler like a ThermalRight XP with a high throughput fan. I saw good load temperatures for an XP90 and Vantec Tornado, but the noise! The Noise!
I'm testing a Delta ". . . -SHE" 120x38mm fan this week which has a throughput of 142 CFM, and a noise-rating in the mid-50's. Ordinarily, this would seem more extreme than the Tornado, but I'm guessing it might be mostly turbulence, which is muffled effectively inside my case. Further, I'm controlling the fan speed through the mobo CPU-FAN header with SpeedFan 4.20, and I believe when I exchange the existing fan with the Delta I can drop the fan speed to the current level below 3,100 rpm, which is almost noise-free. But the Delta should add about 10 CFM to the current throughput. I'll have it spin up to full at the load temperature value.
We have pretty much confirmed that mobo fan-headers on the P4C800 and P4P800 can easily handle the full capacity of all headers combined, but this particular fan has an amperage rating of 0.8 Amp, or 9.6W draw. That is effectively one-third of the fan-header capacity for the entire board.
Listen -- PULL-EEEEZZZ! I have to ask you. What stepping and product code did you get with your 3.2E, and can you confirm that you can unlock the multiplier with the October '04 BIOS revision for the P4C800?