This is year 2010 and where does a person find a computer with MS DOS on it, XP is obsolete and Vista doesn't have any DOS in it ?

The new WD drives are SATA, and how do you work with them in MS DOS MODE, I.E. Drivers ?
All the new Computers coming out these days are Windows 7 and most in 64 Bit mode (If you want more memory).

A boot-able USB drive on an old MS DOS machine?

Does MS DOS  support the modern chip sets etc. ?

I want to change my Grand Children's X BOX 360 drives from 60 Gb and 120 Gb to the newer 250 Gb versions.

Is there any way to do this on a Windows 7 64 bit computer and where does a person get the bin file listed on these pages?