...if you've got the skills, it's usually worth the effort.. Still, you need to be away of the things needed.. If you're going to use Windows, you'll need to purchase an operating system for the computer. Some computer builders will give you all the drivers needed for the installed hardware but you'll need to verify it and once you have the drivers, you'll need to know how to install them and confirm they are the correct versions for your computer.. (A couple of months ago, I purchased a new desktop with no OS. I have a couple of brand new XP boxes sitting around here and decided to use one.. After I install Windows XP, I installed the mother/chipset driver and it didn't recognize a couple of items it should have.. After obtaining an updated driver, it worked fine.)
The nice thing about installing your own operating system and software from scratch is that there is no "junk" on the computer.. It's only got what you put there.. But, because it's only got what you put there, if you make a mistake, you get to fix it.
Hope this helps.