I think you've listed the required steps just fine. Windows 7 should provide all--or at least most--of the drivers you'll require. Drivers for Windows 7 can still be found at the Dell Support site if something doesn't work. After you get Windows installed, just check Device Manager to see if any devices have a "bang" (!). Then you can usually search Dell or the manufacturer for a driver.
It is possible that your old BIOS might cause issues with Win7, but I don't know for sure. The latest on the Dell site is 1.0.13.http://www.dell.com/support/home/us/en/19/product-support/product/xps-630/drivers