Quite a decent systyem you have there, i dont think the Zalman would offer you any better cooling than the CM, in fact maybe even worse cooling, give me your case budget and ill see what i can recommend.
If your on a budget a far better choice would be Cooler Master HAF 912 Plus Case.
Cooler Master adds another new member to the HAF series, the HAF 912 Plus. To carry the mission of providing the best thermal solutions, HAF 912 Plus supports two 120 mm for external radiator and high-end CPU coolers. Furthermore, the spacious interior accommodates two 200mm fans and two-- 120mm fans for better and superior airflow yet, enough to fit 12 devices and high-end GPUs such as Radeon HD5970 and Nvidia GTX 480.
- Superior cooling performance support up to two 200 mm and two 120 mm fans
- Front 200mm fan with brilliant Red LED provides the best airflow to HDDs
- Removable 3.5”HDD cage provides enthusiasts more convenient installation
- Customized neat cable management
- Dimensions 230 x 480 x 496 mm (WxHxL)
- Weight: 8,45 kg
- Motherboard Support: ATX, Micro-ATX
- Front Cooling: 1x 200 mm (19 dB(A), 700 RPM, Red LED)
- Top Cooling: 1x 200 mm (19 dB(A), 700 RPM, Red LED)
- Rear Cooling: 1x 120 mm (17 dB(A), 1.200 RPM)
- Side Cooling: 1x 140 / 120 mm (Optional)
- 5.25" Drive Bays: 4
- 3.5" Drive Bays: 7
- 2.5" Drive Bays: 4
- Expansions Slots: 8
- Front I/O Ports: 2x USB 2.0 / 1x eSATA/ 1x Audio In/Out
- VGA Card Size: Up to 39 cm
Trust me on this for the extra £15 it has far superior quite cooling at stock much better expansion capabilities and is a really good case to build a system into because of all the cable routing holes, i use this to build mid range to high end gaming systems for people all the time.