Why?
A tube is $14 that has enough for 30 processors. What is $14? I spent $200 on a Friday night sometimes - why go through the hassle of buying cheap stuff for about $4 after you ship it, then apply it, and then when you realize "Hey, I could maybe OC more if I had a better compound?" Then maybe buying the artic silver, wiping hte old stuff off, and putting Nervin's stuff on, when you can just buy the stuff you know works, apply it, and forget about it?
You're really looking at a difference of $11 after you factor in shipping for your generic Silicon-based compound as opposed to your Artic Silver. I don't mean to sound snobby or anything, but if you're going to put together a 1 GHz P3 - or even a cheap Duron system - an extra cost of $10 for the kind of performance it may give you is well worth it. You may be able to hit 900 on a Duron 600 with Artic Silver...whereas on the other stuff, you only may hit 800. That's a big difference for $10.
Don't be cheap - your time is worth more than the difference in price - and get the artic silver.