Looking to downgrade my PC (that sounds odd )

Well either sell my main rig or my media center... One of them has to go by the end of the year really. (Both could technically go because my laptop is quite up to the job of supporting me...)

My main rig is:
AMD Athlon 64 processor 3500+
Windows XP Home Edition
1024 Mb RAM Memory
320 Gb Hard Drive
M-Format Dual Layer DVD ReWriter Drive
256 Mb nVidia 6200+TurboCache Graphics
9-In-1 Media Card Reader
7 x 2.0 USB Ports
2 x Firewire Connections
56k Modem
Around £200?
With 17" screen £300?

Media Center is:
AMD 1.8Ghz Duron
512Mb RAM
2 x 80Gb Hard Drives
(Broken) DVD player
nVidia 5200fx
Digital TV Card
£100 ish?

Do they both check out ish? Would put posters up at Uni I think to try and offload them.
Fancied dropping to a mini ITX mobo system (or something like a shuttle) that has enough power to run Ubuntu to play music, browse. I do quite like the Damn Small Linux rigs that are in the DSL store but they no longer ship internationally. In fact after spending 4 weeks using just my laptop at home, I was thinking maybe time to offload the big rigs compelty?