I'm trying to decide between the D-Link DI-524 and DI-624 Wireless Modem/Router for our ADSL internet connection, which will only be 256kbps at the moment.
The only real difference between the two is that one is rated at 54mbps, and the other at 108mbps... I'm pretty sure that this isn't really going to make a difference to me though, as I 'll only be using it to access the net on my laptop, and we probably won't get a connection above 512kbps.
Can anyone give me any advice regarding this? Will it make any difference to my internet speeds or not, and if not, at what speed will it make a difference (ie. if we upgrade to say a 1Mbps connection or greater, at what point will the 54mpbs modem slow us down?)
Your throughput on wireless 802.11g will be 20-25Mbps and down, where how far down depends on such things as physical barriers (walls, floors, etc.) between your computer and the router, interference (neighbors on the same channel, sometimes microwave ovens, sometimes wireless telephones), etc. It is unlikely to ever get into sub-1Mbps range and still maintain a viable connection.
So, to answer your question, with a 0.5Mbps internet connection, it is a waste of money to purchase 108Mbps equipment. In fact, you may be able to find some old 802.11b equipment really cheap. 802.11b would result in a wireless thoughput of ~5Mbps and down, but still faster than your internet connection.
Having said all of that, however, if you will be doing any file sharing among computers on your home network, you will rapidly come to appreciate the faster networks. Remember, not everything you will ever do with your network in the future will involve the internet.
None of this wireless speed discussion has anything to do with the wired network speed. You can get near-100Mbps in-house network throughput by using ethernet cables instead of wireless. All wireless routers (whether 11b, 11g, so-called 108g, or draft 11n) support 100Mbps wired connections as well. Some support 1000Mbps.
Also, what Grumpy said is quite true - you need the speed-boost equipment on both ends, and generally they need to be made by the same manufacturer.