I see it this way...If you get Ultimate you have so many fewer problems. Thats my opinion, Ive had no problems with Ultimate at all. My sister on the other hand who has basic has had all sorts of problems and compatibility issues. Go with Ultimate or stick with XP.
This is a huge misconception. There is no physical differences in the windows kernel on any version. The differences between basic, home premium, business and ultimate are features. They lack features, otherwise there is no actual difference, so choosing to own ultimate over home premium does not make a difference. If it did, as a consumer I would be very angry and feel that I was forced to upgrade. Even though I already feel that way with vista because they feature limit to bait you into spending more money.
The few major differences between Home Premium and Ultimate are an encrypted file system support, which I advise
NO ONE on this forum ever use that. The ability to connect to a Domain level network. At home do you authenticate to an AD server via LDAP directory? Most likely not, so thats also not needed. Ultimate also allows faxing, and a back up feature which is not in home premium. Otherwise they are the same exact OS.
In all honesty, DX10 really doesn't do anything at this point in time. There is a public outcry for MS to release DX10 for XP. There is also a group of developers trying to make an open source version of DX10 for XP. You can still buy a DX10 card which is top of the line and run your games on max settings in XP. The only major differences will be in benchmarks. In actual real time performances, you most likely will not notice a difference, and you will still run your games at max settings.