I got to document this down while it's fresh....
From day 1 (well, that's 2 days ago), my newly Vista imaged lappie cannot get on my home router. Cannot get DHCP address to be exact. In case you are wondering, it's a WRT54G 3.1 with Thibor firmware. Super solid torrent router.
So it was like getting APIPA, and never successfully got on. I tried at work, no problemo. DHCP worked perfectly. Come home, DHCP no go.
So here comes the merry-go-round. Typing "Vista+DHCP" in Google yielded many horrifying results! And most glaringly, this...
Windows Vista cannot obtain an IP address from certain routers or from certain non-Microsoft DHCP servers - http://support.microsoft.com/kb/928233
I told myself... but I have a Vista PC permanently tethered to the same router, DHCP enabled, no issues. I had a Compaq V2000 running on Vista since RC1 and RTM, no problem as well.
And to make it worst, some people claims that the KB article got the registry value wrong:
DHCPConnDisableBcastFlagToggle vs DHCPConnEnableBcastFlagToggle - http://qkhx.com/ontherock/?p=4
Anyway, neither worked. Even tried to disjoin from the domain so I could manually stop Windows Firewall.
By chance Problem Reports and Solution told me to update my wireless NIC drivers. BTW, my D630 has a Intel 4965AGN. Even provided a download link to V126.96.36.199_VT_DRIVERS.ZIP. But deep down in my heart, "Yeah right, as if updating drivers will ever help."
I will investigate further, to isolate whether it is because of the registry key, or the drivers. But as of now, it seems like the drivers is the one that did the trick. And yes, I always reboot after having a registry change. Twice or more, matter a fact, after each change.