Hi and Welcome,

The computer is decent enough yeah, the only big minor is the ATI card, if it is at all possible take a nvidiacard, trust me on this.
And also try to avoid Vista home premium, most software doesn't run that well on vista and if it runs it's usually vista Bussiness.
If you buy a HP (XW4600/6600/8600)you can select the option for a XP downgrade.
And correct me if i'm wrong but in the last link( the dabs -link) i think it is a refurbished computer which means it is second hand one with possible downsides too, so not recommendable.

Just some general advice;
When you' re just starting with Maya you really don't need a big budget machine, just keep the systemrequirements in mind;
https://usa.autodesk.com/adsk/servlet...112&id=7639522

best of luck