3 monitor question

[strausd]

So I am thinking about getting a third monitor for my 2010 Mac Pro. I tried doing this with my tv, but apparently I need an active adapter or another GPU. I saw this (http://www.amazon.com/Accell-B087B-006B-DisplayPort-Single-Link-Certified/dp/B004071ZXA/ref=sr_1_3?ie=UTF8&s=electronics&qid=1285955102&sr=1-3) and am wondering if it will do the trick. If it doesn't work, would a GT 120 work in the new Mac Pros? And if I did end up running 3 monitors on my 5870, would that slow it down at all?

Also, I am considering getting more RAM. I have 16GB right now and would go up to 24GB. I do a lot of After Effects and right now it is limiting the amount of cores I use because of RAM. If I went up to 24GB, I would be able to use all cores.

I only have enough in my budget to get either the monitor setup or more RAM. What are your opinions?

EDIT: Also, if I got a second GPU, I would be able to use my TV as a display for my computer again.

[Hellhammer]

Yes, the adapter you linked will work (alphaod has two of them (http://forums.macrumors.com/showpost.php?p=11098269&postcount=18)). It's hard to say will it be slowed down but 5870 is a powerhorse so I doubt it. If it does, then you can get another GPU (only 30 bucks lost, shouldn't be a big deal and you can save or sell the adapter)

I would get the RAM if it can really speed up your work.

[strausd]

I also have some of the original 1GB sticks in the MP so I actually have 20GB and AE will only let me use 21 cores. I'm not sure which one to get yet, kinda torn between the two haha. More screen real estate would be nice, but being able to use all my cores would be nice too. Also, I've had Photoshop use up all my RAM a few times...