A piece of warning regarding the Windows XP bluetooth driver:

The Aspire 5520/5220/7220/7520 bluetooth Windows XP driver has Windows XPP WHQL driver support only.

The XPP WHQL drivers can install/uninstall fine without bluescreen issue, but not guarantee system compatibility/reliability due to not qualified by compatibility/reliability test.

The driver file for Windows XP driver is divided into three files: (acer-5220-Bluetooth_Broadcom_XP_Driver.part1.exe, acer-5220-Bluetooth_Broadcom_XP_Driver.part2.rar and acer-5220-Bluetooth_Broadcom_XP_Driver.part3.rar). Apparently the original file is too big hence the split into three smaller files. You can download all three files and run the EXE file to start the extraction.

The Windows XP driver setup will start the InstallShield for Wizard WIDCOMM Bluetooth Software and you can follow on screen instructions to complete the bluetooth driver installation. Not much on the Windows Vista driver though, because I am using Windows XP (yes I know) and when I tried to run the SETUP.EXE file in /BTW/ folder, I was prompted with an error message: Bluetooth Software [This installer be run on Windows Vista only].

Alternatively, you can try the Free Driver Scanner.