Geography matters - WiFi is radio waves... Metal messes with them, so if the router is on the other side of the kitchen, or a furnace room, the appliances can effect or even block signal. I have seen large duct-work do the same.
As far as the technology goes, if the router is older, or your computer is older (say, WinVista to early Win7) upgrading may be useful - an 'N' series router AND network card (has to be both) will vastly improve signal and speed. If it is 'G' series, consider upgrading.
Also a wireless to wireless, or preferably wired to wireless repeater or hotspot can be employed (another router of your own hooked to his would do the same thing PLUS privacy)
And finally, if desktop, Wired is much faster and more reliable than wireless.
Your last point, wired is faster and more reliable than wireless. I was surprised to discover that for myself. This may change in the next few innovations. Wireless is still in it’s infancy.