My universal advice on buying new hardware is simple: keep what you have until it falls apart and then buy either the fastest, or 2nd fastest processor/configuration available. This assures you the longest possible life.
So if your laptop has broken apart (as mine did last year), go ahead and get one now, but otherwise you should wait until this fall. If you can’t wait and feel you must buy one now (even though your existing laptop hasn’t fallen apart) then read this article where Mossberg spells out the big upgrades coming this summer.
Think of it this way, would you rather give in to your weakness and buy a laptop now, only to have it be “old generation” in a few months, or would you keep it together and buy the latest, greatest, coolest, newest thing this fall?