Video card upgrade for Adobe CS6 development on Gateway SX2800

I've recently started expanding my production skills to include ray-traced 3D text and animation. I tried to demo BCC extruded text and objects in Adobe After Effects CS6, but the software told me my video card wasn't compatible. Since I am a developer and not a gamer, my choice of cards is limited to Adobe-approved cards for After Effects and Premiere Pro CS6. Logistics aside for the moment, I can pick up a used GTX 470 on eBay for a little under $100. I see some GTX 570s in the $150-$200 range. Would the extra $75 make a huge difference in performance? Are there particular manufacturers I should target or avoid (MSI, PNY, EVGA, etc.) I've happily used PNY memory a bit; are their video cards solid?

I read through the old posts here about upgrading video card on this machine, and I gleaned two logistical issues as well: power supply and case size on the slimline SX2800. I see 600W PSUs for about $60. I have done a little hardware upgrades like hard drives and memory. Anything I need to know about compatibility with PSUs? As for the case size, would leaving the side panel off while the card is in create any problems? I would rather not try gutting the whole machine and moving it into a new case unless that's my only real option. Thanks for your guidance!

The OEM specs (copied from CNET at:http://reviews.cnet.com/desktops/gateway-sx2800-01/4507... )

For what it's worth, I already maxed out the RAM to 8gb.

General
Product Form Factor Tower
Built-in Devices LED panel
Processor / Chipset
Type Intel Core 2 Quad Q8200 / 2.33 GHz
Number of Cores Quad-Core
64-bit Computing Yes
CPU Qty 1.0
Max CPU Qty 1.0
Chipset Type Intel G43 Express
Front Side Bus 1333.0 MHz
Cache Memory
Installed Size L2 cache - 4.0 MB
RAM
Installed Size 4.0 GB / 8.0 GB (max)
Technology DDR3 SDRAM - Non-ECC
Memory Speed 800.0 MHz
Memory Specification Compliance PC3-6400
Form Factor DIMM 240-pin
Features Unbuffered,
Dual channel memory architecture
Configuration Features 2 x 2 GB
Hard Drive
Capacity 1.0 x 640.0 GB
Interface Type Serial ATA-300
Spindle Speed 7200.0 rpm
Storage Controller
Type Serial ATA - Integrated
Controller Interface Type Serial ATA-300
Hard Drive (3rd)
Type None
Optical Storage
Type DVD±RW (±R DL) / DVD-RAM
Write Speed 18x (DVD Double layer)
Disc Labeling Technology Labelflash Technology
Optical Storage (2nd)
Type None
Storage Removable
Type None
Graphics Controller
Type Integrated
Graphics Processor / Vendor Intel GMA X4500 Dynamic Video Memory Technology 5.0
Input Device
Type Mouse,
Keyboard
Audio Output
Type Integrated
Audio Adapter Integrated Audio
Sound Output Mode 5.1 channel surround
Compliant Standards High Definition Audio
Speaker(s) 2.0 x Right / left channel
Mouse
Technology Optical
Interface USB
Features Scroll
Audio Input
Type None
Telecom
Modem Fax / modem
Max Transfer Rate 56.0 Kbps
Protocols & Specifications ITU V.92
Networking
Type Integrated
Data Link Protocol Ethernet,
Fast Ethernet,
Gigabit Ethernet
Printer
Type None
Expansion / Connectivity
Bays 3.5" x 1/3H,
5.25" x 1/2H,
3.5" x 1/3H
Slots 1.0 (total) / 0.0 (free) x Processor - LGA775 Socket,
1.0 (total) / 1.0 (free) x PCI Express x16 - DIMM 240-pin,
4.0 (total) / 2.0 (free) x Memory
Interfaces 1.0 x Network - Generic ( 5 in front ),
1.0 x Audio / video - Line-out,
1.0 x Storage - Ethernet 10Base-T/100Base-TX/1000Base-T,
1.0 x Mouse - SPDIF,
1.0 x Hi-Speed USB - Line-in,
1.0 x Audio - Generic,
1.0 x Audio - eSATA,
1.0 x Microphone - HDMI,
1.0 x IEEE 1394 (FireWire) - VGA,
1.0 x Display / video - Input,
1.0 x Keyboard,
9.0 x Audio
Power
Device Type Power supply
Power Provided 220.0 Watt
Operating System / Software
OS Provided Microsoft Windows Vista,
Microsoft Windows Vista Home Premium 64-bit Edition
Software Microsoft Money Essentials,
Norton Internet Security 2009 (60 days subscription),
Microsoft Works 9.0,
Microsoft Office 2007 Home and Student Edition (60 days trial),
CyberLink Power2Go
Manufacturer Warranty
Service & Support 1 year warranty
Service & Support Details Limited warranty - Parts and labor - 1 year
Dimensions & Weight
Width 4.2 in
Depth 13.0 in
Height 10.7 in
Weight 11.9 lbs