Many eyes may be on the drugstore chains right now. After all, CVS (NYSE:CVS) is due to buy Eckerd from J.C. Penney (NYSE:JCP) in about a month. CVS released positive same-store numbers for May today, with many investors looking forward to the competitive advantage it may squeeze out of Eckerd and musing on the impact of that acquisition on CVS's future.

CVS said that same-store sales in May increased 6.1% over the same period last year. Overall sales gained 7.7% to $2.17 billion. The company also said that over the course of the year thus far, sales have increased 7.8% to last year's levels. Pharmacy same-store sales increased 5.9%, while front-end sales were up a healthy 6.5%.

Not too long ago, archrival Walgreen (NYSE:WAG) reported its own May sales figures. It reported same-store sales up 8.5%, with total sales increasing 12.8%, which were perfectly decent numbers, though a bit less exciting than April's.

On a sequential basis, CVS's overall sales in April were up 7%, just a tad lower than this time around, while same-store sales increased 5.4%. At that time, pharmacy same-store sales gained 7.3%, while front-end sales were up a mere 1.4%.

Investors bid shares of CVS about 1% higher today. As the No. 2 drugstore chain behind Walgreen (and arguably, a much more exciting possible pick than another drug store rival, Rite Aid (NYSE:RAD)), the Eckerd deal has given CVS a boost in esteem, though it may come with some problems of its own, considering it's been struggling under parent J.C. Penney.

Meanwhile, the prognosis for CVS has been good, with its first-quarter earnings providing more reason to consider the stock. There's also the investor sentiment that maybe CVS can whip Eckerd into shape to take on Walgreen in its own territory. With a forward P/E of 20, compared to Walgreen's 27, CVS stock may be a less expensive way to get hooked on drugstores.

Talk to Foolish investors about the Walgreen/CVS rivalry on the Walgreen discussion board.

Alyce Lomax does not own shares of any companies mentioned.