Two great tools for applying and removing heatsink compound:Spreader
: Lop the end off a disposable plastic knife about 1/2" from the end, and taper it for flexibility. (Only taper one side, so the other stays smooth.) If you do heat sinks a lot, use a cheap silicone spatula.Scraper:
Get a sticky note (or cut a small square of printer paper) and curl the ends up so it looks like an extruded teardrop. Use the round part like a scoop to pick up as much of the old compound as you can. This makes it a LOT easier to clean up with alcohol, and works on both white silicon glop and the hard grey stuff Dell uses.
You need a surprisingly small amount of compound most of the time. A dot about the size of a pea is more than enough for desktop Socket 478 and 775 CPUs. You should be able to get a couple applications out of those cheap little tubes. Remember, the paste is only there to fill the tiny imperfections in the CPU and heatsink mating surfaces.
Holy jeez, I thought some early P4 Dells were bad. (Think malleable aluminum foil crushed between the CPU and a heatsink made of accordion-folded stamped sheet steel.)