I've decided to use what I have instead of jumping in with both feet and committing to linuxMCE with all new hardware.
Desktop:HP Pavilion AMD64 3700+ with 1G ram, nvidia 6600, 200G internal, 500G internal, and 750G usb external drives.
Current mythtv client: HP Pavilioin zd7000 with nvidia go5600 video, dead screen but s-video out works fine
Extra: Thinkpad T21, S3 Inc. Savage/IX8 video adapter, dead hard drive, I THINK it supports PXE.
Here are my thoughts, please tell me if I'm being stupid or if I don't understand something correctly. I still need to use my desktop as a desktop as well as the minor amount of internet server stuff it does (web server, e-mail, dns, etc). I also want to minimize the number of re-installs I do. This leads me to believe I should install Kubuntu 7.04 then using the 2CD version, install linuxMCE 0704. Going with a DVD install means less options for things like setting it up to mostly use it as a desktop. Going with 0710 beta means there is a decent chance that I'll have to completely re-install. LinuxMCE 0704 will upgrade to 0710 without issue (if it works as designed).
A couple things I'm not clear on, will the upgrade from 0704 to 0710 also upgrade my system to AMD64 binaries? Will the upgrade include net boot images for AMD64 as well as 32bit images? Am I setting myself up for a load of extra work and just need to suck it up and wait for 0710 to come out "someday?"