For about $100 you can get a formidable performing DDR2 kit which offers a lot of overclocking headroom, so is a future-proof investment with Conroe and AM2 being released very soon.
Being able to run super high clocks close to DDR2-1000 and also running extreme tight latencies of 3-2-2-4, at lower clocks of course, make this memory an excellent all-round choice for all users.
If you plan to run faster than DDR2-800 you must have an i955 or i975 chipset, the older i925 or i945 will not be able to handle these speeds.
An additional plus is that this memory will work well even without any voltage increase. This makes it a good choice for lower cost motherboards which offer only limited voltage options in their BIOS.