In the UK Windows Vista comes in 4 distinct versions and each can be 64bit or 32bit so what version do you really need for your notebook?
Well the cheapest option is Vista Home Basic, however it is only £10-15 cheaper than Home premium and it is exactly that, extremely basic. Microsoft or so petty that they don't even include their shiny new Aero Glass graphical interface let alone much else. Also it is important to note that on some models of laptop this version of Vista will run SLOWER. And the memory requirements are still set at 1024mb/1 Gigabyte to run this operating system reasonably well. This version is best avoided for reasons given below.
The next version of Vista is called Home Premium. Now Home Premium is quite an interesting package as it replaces 3 different operating systems from the Windows XP era in one package. But firstly it enables the Aero Glass graphical user interface (all the glitzy transparent window borders and realtime updating previews of tasks running in 1/8th size popup windows along with the 3D task switcher which also shows a live action preview of what the task is doing. Now these may seem like superficial things to worry about however if you have a suitably powerful graphics accelerator in your notebook (ie non intel or non shared memory graphics chipset from ATI/Nvidia) Vista will activily use the power of the graphics chip to accelerate the speed of Vista Home Premium as a whole so it will actually drain less power from your notebooks processor in it's execution.
This is only the start of the good news. Vista Home Premium has full Tablet PC capability with no restrictions so if you used Windows XP Tablet edition previously then all the Tablet PC specific features will be available to you. Finally with this version of Windows Vista you also have what is known as media center functionality. This is a bit like a simple interface dedicated to movie/music/image playback and recording and very desirable if you have a TV Tuner package for your notebook. Also a remote control compatible with this interface makes using your notebook as easy as using a SKY+ or Cable TV set top box (but you can still use a mouse) So to recap, Vista Home premium is £10-15 more than Home Basic but includes the functionality of Windows XP Media Center Edition and XP Tablet Edition aswell as Aero Glass on top of Home Basic's functionality. This is the version to go for in our opinion for value for money.
Vista Business and Vista Ultimate.
All I will say is there is a few bells and whistles over Home Premium but highly unlikey you will require them for £40-60 more than Home Premium. Vista Ultimate plays a mean game of Texas Hold'em though and can include realtime video desktop backgrounds as oppossed to static images only. My advice is unless you know of a specific feature promoted by Microsoft which is included in Business/Utlimate then really save your money and spend it on making your notebook 2048mb/2 Gigabytes in total to maximise the speed of Vista. If it is already being supplied free with your notebook then don't worry as neither has any less functionality than Vista Home Premium.
32bit or 64bit, why do I need them and what specification is required? Simple enough to answer this one as 32bit and 64bit editions are functionally identical. The only difference is if you have a 4 Gigabyte memory on your laptop you will need the 64bit edition of Vista to utilise it all, otherwise only 3 Gigabytes of memory is accessible by the 32bit edition of Vista. However Vista 64bit edition will only be installable on genuine 64bit processors such as Core2Duo dual core laptops. Core Duo laptops or older can NOT run Vista 64bit edition and will refuse to install so best to avoid purchasing this version unless you know you have a Core 2 Duo processor in your notebook and note just a Core Duo processor equiped dual core notebook.
I hope you have found this guide helpful, this guide does not attempt to compare Windows XP with Windows Vista but is merely intended for people who wish to know which version of Vista they should look for and pay from their hard earned money. Apart from the specific comments about Core2Duo vs Core Duo processors this guide can be applied to desktop machines also as a general rule of thumb.