OK, I've spent the last hour defrosting my freezer
(it had to be done -- I miss frost-free freezers with ice makers!) so I had some time to think about a couple more things I would add.
sagehen03, which ever computer you end up buying, learn how to use it. Sounds obvious, but until you've used it in different conditions (e.g., training at your local lake vs. multi-day holiday diving) you probably won't remember all of the functions. I keep the instruction manual in my log book that goes with me whenever I dive. But learn the various messages/warnings it will give you so you don't become concerned with an unfamiliar message under water. I learned from experience on this one as I didn't understand a warning and decided to end a dive early to be on the safe side. Had I understood the message it was giving me, I would have been able to continue the dive with no problems.
All of my (PADI) instructors are also technical divers/instructors. When went to pick up my computer, one of them showed me how to use the basic functions. Plus, he wanted me to understand how the display and info changes should I ever hit a NDL and go into deco. He wasn't advocating I do so, but wanted me to understand how to do a safe ascent and respect the deco stops required should I find myself in that situation.
Fast foward about 2.5 years. I was diving with a friend on a liveaboard. She had the same computer as me that she bought 2nd hand without an instruction manual. We were doing repetitive dives and needed to plan and watch our NDLs. While getting another photo of something, she accidently went into deco (very briefly) but didn't understand what her computer was telling her to do. She didn't communicate this to me or anyone else on the dive so we only knew after the fact when we all looked at her computer's log. She missed her deco stops so the computer locked her out, told her to stop diving & shut itself off, and the boat policies prevented her from diving for 1.5 days. Had she understood her computer better, she could have done the stops on that dive, and then continued diving the rest of the next 1.5 days. She took as a good lesson and did her nitrox theory course while she couldn't dive.
I know all of this sounds obvious, but on several occasions on holiday, I've witnessed people not really know how to use their computers.