I know, the age is definitely one drawback! Shame it hasn't been superseded by a better version after all these years.
According to google, though, it does support ADSL2+:http://www.google.co.uk/search?q=netgear+dg834+adsl2
and more importantly Netgear's own site:http://www.netgear.com/Products/RoutersandGateways/WiredRouters/DG834.aspx
Not sure what to go with. It seems the QoS might not be tweakable. I might have to go with a higher end router modem.