I had a similar issue with XP awhile back with my wireless... about 20% of the time if you hovered over the network icon (bottom right corner) it would say "acquiring network connection" even though it was working just fine.
Right clicking on the icon and selecting "repair network connection" would fix it until the next reboot, in which it had about a 20% chance of happening again. This was with an el-cheapo PCI wireless card, and letting "Windows manage my network connections" (AKA Zero Wireless Configuration Service being enabled).
I still think it was simply poorly written drivers.
After I upgraded to Win7, I never had that problem again.