There is no "Stereo mix" and "CD player" recording options in the Lenovo ThinkPad R61, T61 (allergedly X61 also, but we haven't confirmed that yet) under Windows XP or Windows Vista.
Those are available in the previous generations of nearly identical machines like T60p
You should contact your Lenovo sales (before you purchase one) and/or support personnel (too late) for the "official" explanation if you feels like it, it is quite funny if you have a sense of humor.
Otherwise, you can see other users' more realistic and down to earth view on various forums
e.g.
Some claimed it is the difference in hardware.
Is different versions of Analog Device's SoundMAX Integrated Digital HD Audio
HDAUDIO\FUNC_01&VEN_11D4&DEV_1984&SUBSYS_17AA20D7&REV_1004 (T61) vs
HDAUDIO\FUNC_01&VEN_11D4&DEV_1981&SUBSYS_17AA2025&REV_1002 (T60p)
[it would be funny if all the new rev. "by design" changes for unspecified reason did is to remove features as some people claimed]
The datasheets from Analog Device seem to say the functionalities are in the hardware.
AD1981HD
http://www.analog.com/en/prod/0,2877,AD1981HD,00.html
AD1984
http://www.analog.com/en/prod/0,2877,AD1984,00.html
"...
- Analog mixer supports recording and playback of signals from multiple analog input sources
..."
and/or the change from5.10.1.4326 to 5.10.1.5370 driver the culpit?
It makes you scratch you head why in the new version's
C:\SWTOOLS\DRIVERS\AUDIO\SMAXWDM\W2K_XP\ADIHDAUD.INF
there is a line
...
HKR,AD1984\\Disable, OutR, 1, 01 ;; Disable Stereo Mix Capture Node
...
Or there is something funny about Lenovo "new and improved" system board design? Nobody can tell you for sure at this time.
You can also check out users of other manufacturers who pulled the same stunt deal with this situation, some have better luck than others.
e.g.
<http://forums.techarena.in/showthread.php?t=708813>
<http://www.techimo.com/forum/showthread.php?t=160431&page=2>