i386 is for 32-bit Intel architecture machines. If you have a 32-bit Intel or AMD CPU, then you want these ISOs.
x86_64 is for 64-bit architectures. If you have a 64-bit CPU, then you want these ISOs.
ppc is for PowerPC architectures. If you have a PPC based system (like the non-Intel Macs), then you want these ISOs.
The SRPMs are source RPMs, but I don't know much more than that. I'm pretty sure you want the "normal" ISOs though.
Also, your thread title asks a completely different question to what's in your post!
You need to burn those ISOs as images to CDs, not as ordinary files. Nero has a "burn image" option in its menu somewhere and other burning software you can get should also have a similar option. You then just need to boot from the first CD (after making sure your CD drive is the first boot device) and installation should commence.
Last edited by Nylex; 02-12-2006 at 12:04 PM.