Redhat free version is now named fedora and you can finde it on fedora.redhat.com . Although beaware that the first version is a bit buggy. When i first installed it i couldn´t update it and install aditional programs. You need to update the updater (the chicken egg situation. So download the update first.
Redhat has a hardware compatibility list, you can find it here: http://hardware.redhat.com/hcl/
A guy has made a guide to install RH9 on a asus m6n which has many of the same stuff as yours, so much of it can be of use. You can finde it here: http://mrhammy2.ath.cx:81/m6n.html
Yours have a different ethernet card, check RH´s site for that.
The 2 most troublesome things is the ati driver and the acpi support. You have to compile a new kernel to get it working right (kernel 2.6), and the ati driver can be of little fun 2. But once running it´s really nice.