That looks like a real pro configuration. Go for it and you will have a lot of fun with a lot of nice sims ...

Regarding the TFT you can't do many mistakes. Dell.co.uk has a special promoton these days:

Technical Specifications Tube type and size / Viewable image size: Active matrix TFT LCD / Diagonal 17.0" (43.1cm)
Dot pitch (mm): .264mm
Horizontal scan range: 31 kHz-80 kHz (automatic)
Vertical Scan Range: 56 Hz-76 Hz (automatic)
Brightness (cd/m2) (typical) / Contrast ratio (typical): 250 CD/m2 typical / 350:1 typical
Viewing Angle: '+/- 60° Vertical, +/- 70° Horizontal
Optimal preset resolution / Highest preset resolution: 1280 x 1024 @ 60 Hz / 1280 x 1024 @ 75 Hz
Display Modes: 31.5 kHz Horizontal, 70.1 Hz Vertical / 31.5 kHz Horizontal, 59.9 Hz Vertical / 37.5 kHz Horizontal, 75.0 Hz Vertical / 37.9 kHz Horizontal, 60.3 Hz Vert. / 46.9 kHz H, 75.0 Hz V / 48.4 kHz H, 60.0 Hz V / 60.0 kHz H, 75.0 Hz V
Connector type: 15-pin D-subminiature analog (blue)
Dimensions H x W x D / Weight: 15.07" (383mm) x 15.92" (404mm) x 7.87" (200mm) / 14.11 lbs. (6.4 kg)

but I wld check the dual use ability of your MAC monitor first. It's already there so it won't eat much.

Cheers - wolfgang