While Fools should generally take the opinion of Wall Street with a grain of salt, it's not a bad idea to take a closer look at particularly stock-shaking upgrades and downgrades -- just in case their reasoning behind the call makes sense.

What: Shares of Hewlett-Packard Company (HPQ +8.51%) climbed more than 2% today after J.P. Morgan upgraded the IT services specialist from neutral to overweight.

So what: Along with the upgrade, analyst Mark Moskowit boosted his price target to $35 (from $30), representing 30% worth of upside to yesterday's close. While value investors might be turned off by Hewlett-Packard's strong share-price action in 2013, Moskowit believes there's plenty of room to run given his view of continued PC stabilization and further free cash flow improvement.

Now what: J.P. Morgan expects HP to generate about $6 billion-$6.5 billion in 2014 free cash flow, but also said that $8 billion is a strong upside possibility. "While our revised 2014 PC growth forecast is not suggesting a major recovery in the making, we believe the potential of market conditions stabilizing after a year of meaningful deterioration could be enough of a catalyst to revive investor interest in PC-related stocks such as HP," noted J.P. Morgan. With Hewlett-Packard shares trading at a cheapish price-to-cash flow 4, betting on that bullishness might not be a bad idea.