First, kudos for stating (1) your budget and (2) the intended use of this computer. I wish everyone seeking hardware advice would follow your lead and do the same.
What do you bring to the table? That is, do you already have a keyboard, mouse and monitor you can use on this computer. If so, your budget will get you a better performing computer. If you need those items too, especially a monitor, your options will be limited. And while audio editing is less demanding than video, it is still demanding, especially with RAM where I would recommend at least 3Gb, with 32-bit and at least 4Gb with 64-bit Windows 7.
As for Pro Tools, I sure don't like their site.
I was looking for system requirements and they seem to be very vague. But what I did find was not very encouraging either.
Windows 7 support is very limited and that is not good. IE8 is not fully supported and that is also not good. They even recommend uninstalling IE8 and that is bad!
It would seem product development with that company has fallen considerably behind. That indicates the company is probably not financially sound (no pun intended). Only the M-Audio version comes close to fully support Windows 7 in both 32 and 64-bit modes. If me, I would avoid Pro Tools and seek out another editing program that does support current technologies, to include full support for 64-bit Windows 7.