Netgear DG834PN - How To Increase Internet Speed

I run vista home premium through a Netgear DG834PN and use an iPad for surfing, emails etc wirelessly.I live in a 3 bed detached house and the router is running in the office upstairs probably 4 metres away max.The house is substantial being ex MOD.My Internet connection is not the best and at max I get around 1.4meg and often far less so I need to maximise my equipment. My speed dropped to less than 0.5meg this morning and it increased again after changing router channels from 11 to 1 but as my speeds fluctuate this could have been coincidental. although the speeds were very low for around 2 weeks running at less than 0.5meg it increased just prior to referral to Openreach so apparently BT would not accept as fault due to line being within parameters.Finally I was using a router supplied by them direct into the master socket and this was no better than my own, so are there any better routers I could purchase to maximise my speed and wireless connection?