ebay watcher script : php?

[rdrnnr]

I'm wanting to write a script to automatically search ebay at a fixed interval, and then email the results. That's the basis -- obviously there would be more rich functionality developed into it, but at this point I want to get a simple version going. I have some questions about this that i was hoping someone here might be able to answer:

How can I set a php script to run in an automated fashion? I'm rather new at Linux, but that's the OS it will be hosted on.

Anyone know of any OS code that does this already? I've looked on sourceforge and this site and (surprisingly) havent been able to find anything in PHP.

Any pitfalls that might occur due to using php? Would this type of app be better suited for Perl?

Thanks for any insight.
-rdrnnr

[procoder]

for nix u need to set up cronjobs which basicly run every xxxxx, to whatever u set it at

crontabs or something, forgot the name

u can set it to run this file(ur script) every x days/time