That should do just fine, I have heard of people running it on a 400mhz pc and they claim it runs ok. However I would assume that whoever was doing that probably had only one tv tuner and probably also had a card like the pvr-250 which does on board mpeg2. You can use cheaper tv cards with it but it will take a lot more system resources and probably won't give results that are as good.
Installation for me was a nightmare because I am running suse 9.1 and using a pvr-250. Now that I have done it the whole thing wasn't that hard but i ran into a ton or problems trying to get my system to recognize my tv tuner and once it had I still had to patch and recompile all of the kernel modules because of the version of my tv tuner.
After getting the tv tuner working properly mythtv was a snap to install, Yast which is suses package manager did a great job taking care of most of the dependency problems which is what most people get stuck on.
The whole process took me awhile to figure out due to the type of setup I was trying to do but it dosn't have to be that painful of a process. If you have a computer which you would be willing to dedicate to the project then you are in luck. There is a linux distrobution call knoppmyth which is ment to be installed on dedicated mythtv systems. It is a distrobution built around mythtv so it comes with support for most of the hardware that you would likley use and is pretty easy to install.
I highly recomend setting it up and if you do I also recomend that you get a nice tv card and the largest harddrive you can afford. My next trick is to get the front end for myth installed on my xbox so I can stream and control all of my recordings from my living room and to also find a simple way to convert mpeg2 to a gpcinima compatible format so I can quickly convert and dump shows on an smc. That way I will be able to grab a few shows hop on the train and have somthing to watch in the morning on my way to work. I have played with movie park in the past and it was ok but with this type of a setup gpcinima could be a really amazing use for the gp32.
