You probably mean data rate mode which is at B and yea it should be at G unless your router is a 802.11b, however B will work with G card but you will only get about 11Mbps throughput.
What I meant by preamble type was how the signal was set to behave like for example is it set for "long" for longer distances or was it set to "short" for more performance or "mix" as both.
Yea definitely change the channel to test if it will keep the connection stable.
WPA-PSK is ok if your card supports it, it is probably since you can go online. Make sure you use TKIP on the client side because this version of WPA only uses the TKIP algorithm.
Have you found any setting on your wireless adapter in device manager?