The AirZO2/Oxy2 combo was specifically designed for use with the Dolphin and is the most obvious choice. Since it's distributed by Scubapro it is also a likely choice for recommendation by your LDS. It's a pretty good, albeit quite expensive, set-up as long as you stay out of deco. The algorithm it uses is not quite up-to--date.
Either the Hydrospace Explorer or DeltaP VR3 are far more advanced, both in their algorithms (RGBM for HSE, microbubbles for VR3) as well as in their features. Either one should also be less expensive than the Uwatec combo. I'd go with the Explorer, but that is a personal preference. And I agree with both previous posts, either one will be a better option than the Uwatec combo, and you made a wise decision to get a ppO2 monitoring device.
All three manufacturers have their respective manuals online as .pdf files. I recommend you download all three and work your way through them. It'll tell you more than we can, and especially the Explorer's manual is worth reading.
Add-ited: DeltaP now also offers the VR2, a less expensive computer. It can calculate up to 4 different EANx mixes for open circuit, as well as be integrated with an O2 cell to for use with SCR and CCR. If HE mixes are not for you, this computer might be.
