How good PC for no-latency?

I dont have å macbook pro.. You got a very good firewire 800 and very fast harddrive!

I got a bad firewire 400 and slow harddrive..
 
I promise you that unless there is something physically broken in your macbook, with the right setup you will be able to get reasonably low latency.
The only really weak link will be the inbuilt firewire chipset (if it's not texas instruments), but there are ways around that (is you have a cardbus or expresscard slot)
 
Your computer is plenty fast, trust me, I know dudes with slower machines than that getting amazing low latency.
 
i've never had such problems in cubase studio 4 on the mac.

although i switched to windows for the greater amount of free plugins (mainly 8505).

i'd say it's a stable recording platform, if you have a decent interface and ASIO drivers.

i'm placing £10 on him not using the right ASIO driver.