Media for Two access points in same house

Two access points in same house

I have a house that is just slightly too large for 1 access point so I have two, a Dlink DI-624 (router & access point) and a Dlink DWL-2100ap. This system works pretty well, but I have found that if you have an issue, Dlink's tech support is abysmal. My question is this, what is the best way to set these two access point up for the best performance and reliability of connection? One issue I can't seem to resolve is finding a convient way to move around the house with a laptop or tablet and have them switch from one access point to another seamlessly. it always seems to involve a little tweaking of the wireless settings to get the connection setup after switching from one access point to the other. Another issue is the wireless client doesn't seem able to switch to the stronger access point. All of my wireless clients are dlink except for the tablet which can use either the dlink client or an intel client (I've got the Dlink usb nic for use with it, it also has an intel 2200b minipci nic in it.

Thanks in advance for any pointers anyone can give me