Here's a good reminder that you can never rest on your laurels: Lowe's is gaining ground against the once unbeatable Home Depot:

Analysts said the results showed that Lowe's was making inroads against industry leader Home Depot Inc. as it sets up newer stores alongside older Home Depot warehouses.

Home Depot has been hurt by weakening sales and perceptions that its customer service is lagging. The difference in the two retailers' performance is evident in sales at stores open at least a year, an important retail measure. Lowe's reported a 4 percent rise in same-store sales for the fourth quarter. Home Depot, on the other hand, has said its quarterly same-store sales could decline as much as 10 percent.

Sometimes the formula of success is as simple (and impossible) as maintaining excellent customer service.