Hi mumra06. Welcome to BT!
Before I spent the money to upgrade the calipers, I would go the cheap route and invest in new pads. Even entry-level brakes these days are a considerable improvement over what was on the market just 10 years ago. One of the ways that manufacturers keep the cost of their brakes down is by specing low-cost pads which, IMO, is counter-productive.
Find yourself some new pads from Jagwire, KoolStop, Shimano or other name-brand and give those a try.
I'm sure that your braking performance will improve but, if not enough to suit you - then consider the calipers to be the culprit. Your new pads can be saved as replacements for the new brakes that you buy.
PS: Even before I swapped pads, I would make sure that the current pads are adjusted properly for height and toe and making solid contact with the braking surface of the rim.
Rob
Wheelies don't pop themselves. (from a QBP fortune cookie)
RobAR, thank you for the wise advice. I will most certainly start with brake pads! I'm hoping they will solve my braking issues.