I have a 'g' ADSL modem/router at the moment but wonder if a newer 'n' standard one will make a difference. We have a desktop pc, a PS3 and a laptop connected wirelessly, plus an Xbox360 connected by ethernet cable (but might go wireless later.) There are also 2 ipod touches. All only have 'g' adapters/capability at the moment. Sometimes my 2 sons complain when one is gaming online and another is downloading music/videos that the game is spoiled. Range is not currently a problem (2 floors, thin walls.) Available internet speed on my line is 4.5Mbs at absolute best at the moment. Will the extra speed/range be of any use? Although my internet speed is limited, will the extra wireless speed help?
802.11g has a nominal data transfer speed of 54Mbps which, in practice, is likely to be nearer 30Mbps. This is still very much faster than your broadband connection and shouldn't be restricting your internet performance.
You can easily check whether a faster "PC to Router" speed would be beneficial by connecting to the router by ethernet instead of "wirelessly", this will give you a data transfer speed of 100Mbps. 802.11n will give a speed of 150Mbps or 300Mbps, depending on the hardware.