I recently purchased an Alfa AWUSO36H 1W wireless USB adapter for my notebook, in order to improve signal strength and quality. I'm currently using Linux Mint 11, and the it uses the RTL8187 driver for this adapter, I'm also using a 4dbi antenna, though I have others.
The problem is that this adapter does exactly the opposite of what it should, actually my internal Broadcom BCM4313 adapter works way better than the alfa. Browsing is slow, some network applications don't even work, pings against Google.com on the internal adapter runs smooth, while in the alfa it gets like 25% packets lost or more!
I'm less them 50 feet from my AP, the internal adapter gets 44/70 link quality, and the alfa gets around 60/70 (iwconfig output).
Also the system always sets alfa power to 20dbm(100mw), then I have to do sudo iw set reg B0 to make it 30dbm(1000mw), but apparently no significant change.
I've installed wireless-compat drivers, no change either.
And worst of all, in Windows 7 it works way more smoothly for browsing, though I couldn't test it properly there.
I hope its a driver problem, even if it's a pain to find/compile Linux drivers for a starter, I prefer it to a hardware problem where I would need to buy another adapter, since I have no money left (except for the cantenna pieces).