Courtesy of Ross Jeffery (rjeffery1@home.com).
"This Registry hack affects the MP3 encoding save rates for the new MS Windows Media Player 8.0 (WMP8) included with Windows XP Gold (all releases).
To make this happen: open Notepad, save the text between the Cut & Paste lines below as a REG file, and then merge it into your Registry by (double)-clicking on it:
-----Begin cut & paste here-----
Windows Registry Editor Version 5.00
This corresponds to 56, 64, 128 and 192 KB/second rates, respectively.
Moreover, you can change the rates using these DWORD [hex] values for each of the Registry entries above:
UPDATE: "This does not apply to WinXP RC1 build 2505 or RC2 build 2509. Microsoft has refined Media Player 8 to allow these values in WMP8 build 8.00.00.4440."
[Thank you Phil Maznyk!]