Sky would only give you a free Sky+ box. You can, if you push hard enough, get that now. If you take out the 3 for £37 offer on the phone, especially with multi room over the phone you can neg. it. However this is a SD, lower capacity box which you buy 'for nothing'.
The V+HD/TVDrive is a HD, higher capacity box which you rent. Should you ever get any problems or fancy a cheeky upgrade its straight forward.
As for which colour you get depends on your network and time of installation
