hey noob question looking for the best linux distro that can handle 1: the largest number of hdds, 2: the largest capacity hdds. building a pvr to run mythtv on.

They're not really distribution limited / related, but kernel limited instead, and I don't think you'll hit the limits with hardware available for mortal users.

Linux kernel can handle "out of the box" up to 64 GB of RAM, see High Memory In The Linux Kernel for details.

I'm not sure how many storage controllers is the maximum, but at least you can have hard disk drives from hda to hdz, as far as I know.

such limits are of little importance with most x86 systems, but can be of concern when dealing with other architectures such as the alpha processor.