Hi All
I have been using Windows 7 since February and I can say it is the best Microsoft OS ever.
I have been working with computers since the early 80s, (With various OS) and while I would not recommend Vista to my worst enemy, I would have no problems recommending Windows 7.
Download the Windows 7 upgrade advisor
http://www.microsoft.com/windows/windows-7/get/upgrade-advisor.aspx and this will tell you if there are any problems with hardware or software you use.
Although manufactures may not provide drivers for some of their equipment (My HP printer is one) Windows 7 contains plenty of basic driver software onboard, (My HP Printer works sweet as a nut) plus in most cases a Vista driver will work.
Compatibility mode is included with Windows 7 and it works well. (The compatibility mode in XP was a fingers crossed system)
If all else fails, if you have the Pro or Ultimate versions of Windows 7, you can download a free Virtual version of XP that integrates (You don’t need to switch Operating Systems) with Windows 7, so pretty much all bases are covered.
When buying a new computer I would recommend the 64bit version of Windows 7 as this is the future, however a lot of older hardware was never designed for a 64bit OS, so unfortunately you may need to upgrade some of your equipment.
If you are upgrading, go for a second hard drive and have a Dual Boot system, that way if you really need some old stuff, (That doesn’t work with the 64bit version of Windows 7) you can boot back into XP when you need to use it, and use Windows 7 for everything else.
As to problems booting, try updating your Motherboard BIOS, as it’s unlikely to be an XP problem, also check to make sure your computer power supply is big enough for all the hardware you have inside. (This is another cause of booting problems, and the fact that it works with less hardware connected could indicate a power supply problem)
Hope this helps
Bill