The reason I don't do much, if any, illustration work is that I have no talent for it, I couldn't design my way out of the proverbial paper bag.
I have Photoshop CS6 13.0.6 and legacy versions of Illustrator and InDesign, from my DTP days, which I use for heraldry work.
I've always been of the opinion that it is in fact a very good idea to upgrade a legacy computer to its maximum capabilities.
I'm happily working away—well, I've been disabled/retired for about a decade now and I'm on my eight decade on the planet, so it's little work and a lot of pleasure activity on my computers—on my two working legacy computers, the specs of which follow at the bottom of this message for the sake of thoroughness. They're both eight years old, and I work on both of them simultaneously with shared keyboard, mouse, and rudimentary tablet
1.— Intel Xeon Mac_Pro1,1 [late 2006] 2.66 GHz Quad; 16 GB RAM; mutant/flashed, factory-overclocked 875/1225 "Apple PowerColor" ATI Radeon HD 5770 with 1 GB of GDDR5VRAM driving side-by-side dual 22"/24" monitors [shared with the G5-Quad] in Extended-Desktop mode; Mac OS X Lion 10.7.5 and Snow Leopard 10.6.8 boot drives; intrusive Spotlight and frivolous Dashboard permanently disabled; USB wireless 'n' available but connected to the Internet and networked via wired Ethernet. FW Epson 2200 and Ethernet Samsung ML-2850ND printers; 2 X Back-UPS RS 1500 XS units.
2.— 2.5 GHz Power Mac (PPC) G5-Quad; 16GB RAM; mutant, flashed 550MHz nVidia GeForce 7800GTX 1,700MHz 512 MB of VRAM; ATTO ExpressPCI UL5D LP SCSI card; Mac OS X Tiger 10.4.11 and Leopard 10.5.8 boot drives; intrusive Spotblight, Dashboard and Time Machine permanently disabled; dual 22" monitors [shared with the Mac Pro Quad]; USB wireless 'n' available but connected to the Internet via wired Ethernet; FW flatbed scanner; 2 SCSI scanners (one tabloid-size transparency scanner and a film scanner); various internal & external HDs; FW Epson 2200 and Ethernet Samsung ML-2850ND printers; 2 X Back-UPS RS 1500 XS units.
I also have a working G4, the last Mac model to boot in Mac OS 9.0.2 as well as in Mac OS X, a working G3 converted to a G4 via a ZIF CPU upgrade, and a MT G3 monster (size wise).
Two laptops: 1 Power Book and one Toshiba laptop which I take on trips so I won't be too upset if it gets lost or stolen.