The Tek-5 is a much nicer light IMO.
From the description, to me this is the best selling point for getting the Tek over the Nova, "...with individual parabolic reflectors for each bulb made from German Tek 96% reflective aluminum..."
BTW, I happen to own that 36" Nova Extreme. It runs loud, and it doesn't always fire up when run from a timer/controller -- sometimes needs to be switched on manually to get it to kick in. The Nova does not have individual bulb reflectors -- and yes, it makes a huge difference.
AFAIK, the Tek-5 is passively cooled -- so you may want to purchase a fan to run across the top of your water.
Another fixture worth looking at in the same price range is the Aquactinics TX5 -- I think I'd go for this over the Tek.
For what it's worth, I wouldn't waste my money on the Nova Extreme. I'm sure others will have varying opinions.