First HTPC but which barebones to go for

After putting up with poor support, functionality and GUI's on dedicated off the self media streamers I have decided to look at building a low cost but good price/performance HTPC. I want to be able to stream SD and HD movies and family photos from my ReadyNAS over 100mb ethernet and will have XBMC as my front end. I haven't decided on the OS yet but Ubuntu or Windows7 Home Premium are likely, I am also considering XBOX Live. I might also use the PC for web browsing but this is not essential.

I am looking at barebones PC's and have identified the following as potential candidates;

Acer Aspire Revo r3700 - includes 2GB DDR3 memory and 160GB HDD.
Zotac Zbox ND22 - I will need to add 2GB memory and an HDD or SDD.
Zotac Zbox ID11 - I will need to add 2GB memory and an HDD or SDD.

Are there any others I should consider? What does you think of the above?

Could I put together a similar spec PC from parts and if so what would you recommend. I need a small form factor as the HTPC will go into my AV cabinet under the TV.

Any help appreciated.

Thanks

David

Here are links for the Zotac build;

Zotac ND22 http://www.ebuyer.com/product/237146
RAM http://www.ebuyer.com/product/159916
SSD http://www.ebuyer.com/product/247005 or http://www.ebuyer.com/product/160730

I wasn't sure if 30GB SSD was enough should I go the Windows7 route.

£287 for everything or I could get the Revo r3700 for £200. I know this isn't up to the spec's of some HTPC's I read about here.

David

well honestly, is you only want an XBMC front end and nothing more,
the Revo r3700 is fine for 1080P...

if u plan to do more like play NETFLIX or HULU HD
and any other stuff like UseNet/Ripping/Video Editing Tasks,
you'll need a different box....