My only experience with Buffalo are their network storage devices, which are excellent.
The first thing you need to try is a firmware update. I had some serious issues with my Belkin wireless G router - there was a known issue with my particular model and it's been fine ever since the update.
If a firmware update doesn't fix the problem, or it's already up to date - throw the problem to Buffalo, or take it back to the shop and get something else!
Also, as mentioned, a wired connection is going to be a lot more reliable than wireless. The only way to get more than 54Mbps is to buy a G+ (or onwards) router with a compatible wireless device. I think your best plan is to install a gigabit switch, then plumb Cat5 in all around your house and forget the wireless - then the only thing you get get pi**ed off about is your Internet bandwidth :D
lmao, actually it wouldn't be too much of a pain to plumb some Cat5 into the living room - it's only through the main bedroom wall, and there is already a hole there from when the cable company trailed the cables through the house to install the cable tv from the main point in the bedroom.
As for usage - it's just for surfing the net, nothing hardcore like online gaming. I just feel cheeted getting half the speed I'm paying for.
No idea what the wireless card is spec'd for - it's built into the laptop (Sony Vaio). Looking at the modem/hardware options through control panel I get the following listed device...
Device: HD Audio SoftV92 Data Fax Modem with Smart CP
Driver date: 01/10/04 (this could probably do with an update, right?)
115,200Mbps is the max listed transfer speed and is currently selected.
Ideas?