Upgrade dual GTS 450s or revert to single?

Hey guys, I'm in a bit of a conundrum with my setup right now. Currently I'm running 2 GTS 450s and I'm not even sure if I have them SLI'd right now because of how I wanted to use them recently. I reconfigured my room so that my computer can run movies on my TV along with my 2 monitors on the desk, so I have 3 total and I think I had to disable SLI to get that running so that's the first problem.

The second problem is now my video lags a little bit when I'm playing certain games (Diablo 3, SC2, and borderlands 2) when I'm trying to watch a movie or tv on my other monitor (at 1920x1080) or on my tv at 720p. Before I added the TV component I could play my games on max or near max while watching an HD movie on my 2nd monitor with no problem, both at 1920x1080. I'm fairly certain that SLI was enabled when I only had the 2 monitors but when I added the third I would only get video on 2 of the 3 monitors so I had to disable the SLI but keep both cards to get picture on all 3.

So my real question is would it be possible to fix the SLI problem to work on all 3 monitors, or would it just be easier to upgrade to a single higher powered card that can handle 2 1080p monitors and a 720p TV at the same time?

I don't have my full system specs on me right now since I'm at work I only have my "windows experience" print out since I sent it to someone on Facebook the other day and I'm at work but ill edit this when I get home with full specs. I can probably fill in anything missing from memory that you would need. Here's the widows print out:

More details about my computer


Component Details Subscore Base score
Processor Intel(R) Core(TM) i5 CPU 750 @ 2.67GHz 7.3
5.9 Determined by lowest subscore

Memory (RAM) 16.0 GB 7.5
Graphics NVIDIA GeForce GTS 450 7.2
Gaming graphics 4095 MB Total available graphics memory 7.2
Primary hard disk 323GB Free (466GB Total) 5.9
Windows 7 Ultimate

System
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Manufacturer BIOSTAR Group
Model T5XE CFX-SLI
Total amount of system memory 16.0 GB RAM
System type 64-bit operating system
Number of processor cores 4

Storage
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Total size of hard disk(s) 4192 GB
Disk partition (C  323 GB Free (466 GB Total)
Disk partition (D  458 GB Free (1397 GB Total)
Disk partition (E  213 GB Free (932 GB Total)
Media drive (F  CD/DVD
Disk partition (G  922 GB Free (1397 GB Total)
Media drive (H  CD/DVD

Graphics
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Display adapter type NVIDIA GeForce GTS 450
Total available graphics memory 4095 MB
Dedicated graphics memory 1024 MB
Dedicated system memory 0 MB
Shared system memory 3071 MB
Display adapter driver version 9.18.13.1070
Primary monitor resolution 1920x1080
Secondary monitor resolution 1920x1080
Secondary monitor resolution 1280x720
DirectX version DirectX 10

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I like to stick with nvidia for the most part and my board will support crossfire or SLI with 2 pci-e 2.0 x 8x or single 16x speeds. I don't want to spend more than around 150$ but I don't know if the cards in that range would be better than my current config.

Any help would be appreciated and I can fill in any missing info questions you have just let me know. Thanks guys.