RAM

I have a p4 2.66 ghz processor and 512mb of ddr ram how much of the ram should I allow the program to use?

[TauCeti]

There is some detailed information in the readme.txt

The P-1 factoring step prior to running a Lucas-Lehmer test is more effective if it is given more memory to work with. However, if you let the program use too much memory then the performance of ALL programs will suffer. The good news is that 98% of the time the program uses less than 8MB. In fact, the program will work just fine if you instruct the program to use only 8MB or less.

The program will only use more then 8 MB for 2% of it's running time. If you can spare the RAM and do not have other applications demanding a lot, i would suggest 256MB. If you are unsure about your other applications, choose 100 MB or leave it at 8MB.