Let the hive mind of Engadget get that for you.
"I'm pretty much a complete noob when it comes to camera stuff. My wife loves to take pictures, though. So much so that she literally wore out her first point and shoot camera, and the Kodak Z712 I bought for her less than two years ago is starting to act up as well. To compound the matter, we are expecting our first born sometime next year. I fear the Kodak just isn't going to cut it any longer. What would be the best starter DSLR to get? She hates missing photo opportunities due to camera 'lag' so speed would definitely be at the top of the list. Photo quality and features would be next. Price should be no more than $800. I'm not interested in video capabilities."
The 420/430 SKUs are listed at the following link and I've compared the available OS's below.
http://www.dell.com/content/products/productdetails.aspx/desktop-xps-430?c=us&cs=19&l=en&s=dhs
XPS 420 32-bit (1 SKU):
Genuine Windows Vista® Home Premium w/ Digital Cable Support SP1 [Included in Price]
Genuine Windows Vista® Ultimate w/ Digital Cable Support SP1 [add $150 or $5/month-1]
XPS 420 64-bit (2 SKUs):
Genuine Windows Vista® Home Premium Edition SP1, 64-Bit
XPS 430 (2 SKUs):
Genuine Windows Vista™ Home Premium w/Digital Cable Support, 64-bit [Included in Price]
Genuine Windows Vista™ Ultimate w/Digital Cable Support, 64-bit [add $150 or $5/month-1]
Based on this a) someone can buy the 430 from Dell and use DCTs from elsewhere (buy them online or use ones you already have) and b) I'd expect Dell to add the DCT tuners to the 430 configuration options very soon.
Base price of the 430 is a lot more than the 420 though, so I hope they either keep the 420 around or drop the 430's price to match the 420.