Saw your comment on my blog about GC isos. While I won't provide any links to them, I can tell you some good computer specs to have:
Windows 7 64-bit
NVIDIA GeForce 8400 GS 1GB
4GB RAM
AMD Athlon II X2 @ 2.80 GHz
Internet download speeds of around 1.4MB/s
That's what I have and believe me, I get my stuff quickly (unless server in question is a dooche), and I play most GameCube games at or around full speed. ^^