There is no such thing as a "Home Premium Vista" disc, or an "Ultimate Vista" disc!!!! ALL VISTA DISCS CONTAIN ALL VERSIONS OF VISTA. The thing that determines what version of Vista you have is the License Key that you have. You may have a sticker on it that says "Vista Business" or "Vista Home Premium", but IT IS A LIE. Your disc *may* be forced to install a certain version, (see "CUSTOM OEM Vista Disc" below) but it still contains all versions. It is possible to modify this disc so you can use it to install any version (that you have a license for).
There are many types of Vista discs out there, here is the "official" terminology of what they mean (each of these discs come in 2 versions, 32bit and 64bit):
Anytime Upgrade Disc This disc contains all versions of Vista, unmodified as Microsoft is shipping it. It is sometimes included for free with your system, or can be purchased online for under $10. This purchase price does NOT include a license or serial number, it is only the installation media. It is intended so you can upgrade from one version of Vista to another by purchasing a license online. This is the type of disc you need to do a clean install.
Recovery Disc These disc(s) contain an image of your computer as of when you got it. They can be used to restore your system to the EXACT state as when you first opened the box and turned it on for the first time. Vista is on these discs, but so is all the bloatware. The images are encrypted, and cannot be modified to be used for a clean install. It's best to burn these for yourself using the included recovery disc creation tools, but you can also usually buy them.
Vista Retail Disc These discs are the ones you buy at the store in a shiny Vista box. They include a license and serial number for a particular version of Vista. The contents of the disc are IDENTICAL to the contents of the Anytime Upgrade Discs. These discs are expensive because you are buying a license along with them. You already have a license for Vista on your laptop, so there's no need to buy another one to do a clean install.
OEM Vista Disc These discs sometimes get shipped with your system, and are IDENTICAL to the Vista Retail and Anytime Upgrade discs. The main difference here is in the licensing from the OEM (HP, Dell, etc...).
CUSTOM OEM Vista Disc These seems to be showing up more recently, especially with Dell systems. Some OEMs ship Vista discs that have been modified to include changes such as forcing the disc to only install a certain Vista version, and also include integrated drivers. You can probably do a clean install with them, but you might need to modify the disc before you do it. See the next section for details.