We can give you better advice if we know what the main uses of this computer will be? Gaming, internet, work, etc.
For the PSU I trust Antec and Thermaltake, but other people have their own trusted brands.
The motherboard has network and audio covered if you need to shave off the costs of the add-on cards.
Overall it looks like a fairly decent budget computer. I would put it closer to 2-3 years instead of 3-5, but there is still some upgrade potential that can be exploited later on to extend that.
Also, I've been reading up on Arctic Silver 5 Thermal Compound and I've seen a few spots where it claims to be permanent and will never be able to be removed.
You got me curious so I looked this up. According to the instructions on Arctic Silver's website that is partially correct. You won't be able to remove all of the Arctic Silver from the microscopic valleys of the heatsink with standard tools. However, this does not mean that you cannot replace the processor or heatsink. Just clean off as much of it as you can and then apply a fresh layer when installing.