Windows Vista

Is it worth purchasing now, well most likely not if your hardware is not very current, say last year or so's tech as your likely to run into driver issues.

Bugs, well all OSes have bugs when first released and continue to mature with age when more and more bugs are fixed, their is no way for a developer to really plan for all eventualities and the multitude of various permutations of hardware and software that folk use as no two PCs are really alike.

The majority of OSes tend to be alot more robust by the first service pack, but some early adopters like to play with latest technology, personally I have no issues with Vista as it works fine for me, the odd not so good driver, Nvidia's drivers are kinda buggy at present, but thats not an MS issue.

Depending on version of Vista bought, you can do the following.

Full Retail and OEM, you can do both in Clean installing from booting to the DVD or an upgrade install from within the previous OS, however many variables can halt your progress here, see link below.

Upgrade versions, well as they are called are upgrades to the previous OS, however this time, they are ment to be installed from the GUI of a previous OS, and do not clean install from booting to the DVD as in past upgrade disks would in which all you had to do was pop a full/upgrade older OS in the drive to validate.... and you could clean install, this time you can clean install via a workaround, but it has you installing Vista twice.





Vista upgrade advisor will highlight potential areas of concern
http://www.majorgeeks.com/download.php?det=5485


Upgrade Matrix of which previous OSes can be upgraded or which have to be clean installed.
http://www.microsoft.com/windows/products/windowsvista/buyorupgrade/upgradepaths.mspx