I need to change my router just now and I'm on ADSL at the moment but may change to cable (Virgin) in a few months time.

Would the Vigor 2820 be ok in both circumstances or would I be better with something like a 2920 plus and an ADSL modem (120) just now and drop that when I go cable?

The 2820 would be fine for that.

WAN1 is specifically for ADSL but WAN2 is just an ethernet port which is what you will get on the back of the 2920.

The only thing to consider is that if you do use WAN2 then you can not use the 3G USB backup. With the 2820 its ADSL plus cable or ADSL plus USB. You can NOT do Cable plus USB.

many thanks for that... Appreciated