I had (and still have) lots of problems porting everything from XP to VISTA and 5 months went by. My contractor has asp.classic, asp.net 1.14 and asp.net 2.0 applications either in mssqlserver 2000 and mssqlserver2005 with third party componentes (custom backoffices, crm dll's, ironspeed, etc).
Everything is debuging and running. Vista Home Premium misses Windows Integrated Authentication that you can find in Vista Ultimate.
Im currently porting some projects code to the new visa 3dsecure but still face lot of issues, regarding the server certifications and certification access by code either in asp.net 1.14 or 2.0.
Even to register the components they hidden it somewhere in c:\windows\system32\.. They removed the mailserver from IIS7, there goes a new issue to develop applications that handle e-mails. You can use IIS7 to relay emails. yah.. but isnt the same right? And what about UAC? disable it! its annoying! its awkward! Trying to follow what linux has for years... Its so annoying that if you are willing to do some large administrative task you better shut it off... (and when you do it, remember to do it for good!). Microsoft this time made it big. A big crap that is.
Theres a rule of Thumb about porting stuff that is keep support for old versions or else your clients will run away. On time that wins do not mess.
They tried by all means for you to move all your codebase to the new asp.net3.0 VS2008. But they fail it to do so, because theres still too many apps in the old versions. And not everyone has the time/resources to waste porting code because of a company marketing politics.
Not to mention the nightmare to port everything to IE7 and the security issues regarding running embeded objects as flash with some degree of complexity (xml and remote scripts)... that is a new battle every day but some of the fault are to be shared by adobe/macromedia and their daily changes in the flash plugin.
If you arent wealling to go back to XP and want to keep VISTA to develop, your best bet its to go Windows Vista Ultimate.
Microsoft made me waste to much of my precious time! Microsoft is crap!