I've built countless computers over the past decade, both for myself and for others. Although I prefer it over buying pre-fab machines because the lower cost (for comparable components) and a higher degree of customizability, there is the hassle of picking out all of the components, dealing with individual manufacturer warranties, and installing all of your own software. If you do not have the time to do this, and do not enjoy fiddling with computers, this is probably not the way for you to go. As an aside, I've seen many people make stupid mistakes while building their own computer like forcing the RAM in backwards, cracking their CPU die when seating the heatsink, forgetting thermal compounds, etc... so please make sure you know what you're doing before you attempt building your own system.