I just bought a HP Pavilion G4-1212TU laptop and put Ubuntu 11.10 on it. WiFi works badly. It can usually connect (though showing a lower strength level than when the laptop is in Windows) but sometimes immediately, sometimes after a while, the connection becomes so bad as to be unusable.
That is, the connection strength shows the same number of bars, but TCP/IP requests seem to fail or packets lost.
HP doesn't seem to have any LINUX/Ubuntu drivers for the WiFi for this laptop.
$ lspci -nnk | grep -i net -A2 01:00.0 Network controller : Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller [14e4:4727] (rev 01) Subsystem: Hewlett-Packard Company Device [103c:1795] Kernel driver in use: brcmsmac 02:00.0 Ethernet controller : Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller [10ec:8136] (rev 05) Subsystem: Hewlett-Packard Company Device [103c:166d] Kernel driver in use: r8169