Health–
A Dell bundle or the like is probably what best suits your needs.
Your requirements are simple enough that the cheapest, slowest PC sold nowadays will be sufficient.
BTW, all (or possibly almost all) PCs sold nowadays include a keyboard and mouse.
What is your price range limit?
ItcheSrulik–
Dusting off the memory vaults, I seem to remember RDRAM requiring paired memory, but that was about it.
bombmaniac–
The 480 MBPS USB speed is for USB 2.0
Nowadays, new machines may come with USB 3.0, which is several times faster.