I've just set up my small home wireless network. I have a desktop PC with Win XP SP2 pro for which I just bought a MSI PC 54G2 wireless PCI card. I have access to the internet through this computer by a DSL USB-only modem.
The other one is a laptop (a compaq presario 2108US) with built in wireless networking capabilities and Win XP home SP2.
I managed to set up the wireless ad-hoc network and now I'm sharing files, printers and the internet connection. But I'm having some problems with the latter. The connection in the laptop comes and goes every time. For instance, when I use trillian on the laptop the MSN connection keeps dropping. And when this happens I can't load any pages.
Funny thing is that it seems that this can be avoided as long as I have permanent network activity. For instance, if I play an MP3 on the laptop from the desktop or by downloading files and such. But as soon as any constant network activity ceases I come back to the same problem.
USB, is being put to sleep by the power managment. Trash the USB and use ethernet. Need to set power managment up not to powerdown the needed ports. MS is not smart enough to know you are sharing that port.
If at all possiable get yourself a wireless router and get away from adhoc. You will gain performance and better security, firewall.