Two questions relating to overclocking and cooling
 

I'm planning on over clocking the AMD 64 CPU and my main concern is keeping it cool.

Right now, I'm looking at getting Zalman CPU Cooler (Pretty much the only decent cooler around this town). Anybody have any issue with this particular brand and AMD 64 combined?

Also, on my old computer, I'm using ATI 9550 256 MB DDR and I'm wondering if plugging in a second monitor via the DVI-I connector will have any performance issues or if it's gonna cook the chipset.

Edit: In fact, there's a lot of cooling for all sorts of components (HDD, VGA, CPU, Case, etc). Just what is necessary and what isn't?

I don't know about the Athlon 64, but in regard to the 9550 cooling - the additional monitor shouldn't increase the load on the processor substantially but if you're worried about it you can do what I did with mine, go to CompUSA, pick up a $10 chipset cooling kit, and just mount the small 30mm (rough guess) to the heatsink of the 9550. I've got a Gigabyte 9550 card setup like this and it stays nearly cold to the touch even when I'm gaming.

I have a Zalman CNPS7000 on my Athlon 64 and it works great. It's usually running less than 10 degrees C over ambient slightly overclocked. (2200 @ 2255 right now. I haven't really tried going higher.) It's also quiet, especially compared to the HS/F I have on my old Athlon Thunderbird which sounds like a jet engine when you're sitting in the cabin.

I wouldn't say any extra cooling is necessary if you're not really pushing your hardware. Replacing loud stock cooling with something quieter is not unheard of. I think adding more case fans tends to make more noise rather than actually making the cooling more effective. I doubt anyone really needs more than two or three. I can't think of extra hard drive cooling ever being necessary as long as your case has decent ventilation, and even if it doesn't, the solution is to make your case have decent ventilation instead of actively cooling the hard drive.

The Zalman is the best air cooling for OC'ing besides the XP-90 or XP-120 (but it is quieter than them). With similar air cooling I took my room-mate's 3000+ winchester 0446 from 1.8 to 2.6 rock stable at 1,55volts. temps never break 50c on load. Newer winchesters don't clock as well, my 0504 can get 2.3 stable but any more than that requires more voltage than I care to give it.

There are 2 good forums for Overclocking needs that I could refer you to, but I would rather not post it in this thread. PM me if you wish to see how deep the rabbit hole really goes. (is that the right quote?)