I've figured it out; here is the solution for posterity:
Problem:
Creating an alias to the local computer's netbios name (windows xp
sp2)
Solution:
1) Add the alias in the registry, using HKEY_LOCAL_MACHINE\SYSTEM
\CurrentControlSet\Services\lanmanserver\parameter s\OptionalNames
Ref:
http://www.jsifaq.com/SF/Tips/Tip.aspx?id=0062
2) Disable the Windows XP SP2 'loopback check' ("authentication fails
if the FQDN ... that you use does not match the local computer name"
Ref:
http://support.microsoft.com/default...b;en-us;896861
Tips:
Enabling account logon events in local security policy showed login
failure events 537 having a status code 0xC000006D
(STATUS_LOGON_FAILURE); checking eventid.net (
http://www.eventid.net/
display.asp?eventid=537&eventno=194&source=Securit y&phase=1) led to
the solution.
Mathieu: Setting DisableStrictNameChecking was not necessary because
XPSP2 by default uses only NTLMv1 (non-kerberos) authentication; if I
had been using a server OS, NTLMv2 would have been enabled and
DisableStrictNameChecking would have been required. But if you hadn't
replied, and I hadn't started my google search using that term, I
never would have gotten anywhere

Thanks!