Your link isn't working, but I just used the last one I posted (it has the same data on it).
My take on the differences between the $499 Vostro and $729 Vostro:
a. If you have a monitor you like already, no need for another one. If you wanted a LCD flat panel and you didn't have one, this $729 package provides one.
Link to the monitor, http://accessories.us.dell.com/sna/product...mp;sku=320-5123
b. You go from a dual-core processor to a quad-core. Not necessarily important, really...but the quad-core is a step up.
c. You go from an 80GB hard drive installed...to a 250GB hard drive. Depending on what you do on your system, not necessarily important. My personal view has always been that it's much better to have more space than you anticipate using.
When hard drives went to 100-plus GB, I said to myself: "I'll never have any use for a hard drive that larege." That was before I started capturing/recording movies from TV, sports events from TV, playing with .mp3 music files, etc. I now daily use two systems with a total hard drive space (currently) of about 2.5 terabytes (5 500GB drives).
d. You go from 1GB of RAM to 3GB. 2GB of RAM will cost about $35-40 today and more RAM is always better.
e. You go from a DVD-ROM drive (which cannot burn) to a DVD burner (more flexibility).
Now...I hate to say this but it appears to me that your offerings in the UK from Dell...don't correlate well with what is available in the US. Pricing, selection...big differences, IMO.
The only way to know for sure what's available to you...would be to talk to a Dell rep in the UK and let her/him know what you want and provide the references here in the US.