That can help some, but it isn't everything. Timing amoung other things help. Getting your entire body into the serve like Roddick and not just serving with your arm helps a ton!
Here are the specs on your racquet. I do not know if you use the 95 or the 110. But this racquet does have a low power level.. If you are using the 95, you can try lowering the tension some, but you will lose control.
Midplus Specs
Head Size:
95 sq. in. / 613 sq. cm.
Length: 27.25 inches/69 cm
Strung Weight: 9.8oz / 278g
Balance: 6 pts Head Heavy
Swingweight: 328
Stiffness: 61
Beam Width: 22 mm/25 mm/23 mm Dual Taper Beam
Composition: 60% Graphite, 10% Hyper Carbon, 30% Fiberglass
Power Level: Low-Medium
Swing Speed: Moderate-Fast
Grip Type: Cushion Aire Conform Perf
String Pattern:
16 Mains / 20 Crosses
Mains skip: 7T,9T,7H,9H
One Piece
No shared holes
String Tension: 50-60 pounds
Oversize Specs
Head Size:
110 sq. in. / 710 sq. cm.
Length: 27.5 inches / 70 cm
Strung Weight: 9.6oz / 272g
Balance: 6 pts Head Heavy
Swingweight: 318
Stiffness: 63
Beam Width: 23 mm/27 mm/24 mm Dual Taper Beam
Composition: 60% Graphite, 10% Hyper Carbon, 30% Fiberglass
Power Level: Low-Medium
Swing Speed: Moderate-Fast
Grip Type: Cushion Aire Conform Perf
String Pattern:
16 Mains / 20 Crosses
Mains skip: 7T,9T,7H,9H
One Piece
No shared holes
String Tension: 53-63 pounds