Any sane investor would love to see a stock he or she owns double in six months' time, which is exactly the case for investors in longtime laggard Hewlett-Packard (HPQ 0.04%). And while the company's stock had been punished over the last several years, and for good reason, it's not sporting the bottom-barrel valuation it was months ago. It's true HP remains relatively cheap. Just how much opportunity still remains for investors interested in buying at today's levels? Not much enough to make it a buy, as Fool contributor Andrew Tonner explains below.