I do have a Vigor 120 modem I can use, so the lack of a ADSL modem on the 2925 is not an issue. However, looking through the specs, there seems to be very little real-world difference for a small office with 5 people connecting (server and pritner by wire, laptops by wireless). However, the price variation is up to 30%. Is there any compelling technological reason (excluding the lack of ADSL on the 2925) why I should go for one over the other?

Many thanks,
Steve

One is SOHO the other is SMB
The main difference is the through puts, NAT sessions, VPN and firewall features,
I don't think you get things like tagged dot1q VLANs and Multiple IP subnet alias' (the 2760 is port based only)

there is a comparison chart here too
http://www.draytek.co.uk/products/comparison