I wouldn't bother with either CS2 or CS4. Most of what is in CS4 is Intel-only, and either the original CS, or CS3 would be best. CS is all PPC, and will give the best performance on a G4, vs. CS2 or CS3.
Dear me, there are over ten-thousand programmes that you can run on a G4, and if you include the classic environment, you can run things like Framemaker, which is crucial to my work, and the last Mac version of it is bluebox, so it needs OS9 to run, either via Classic, or Sheepshaver.
(Adobe never released an OSX version of FM7, or later.)
Let's not forget Corel suite (Corel Painter IX) either.
There are a variety of Intuos drivers, and you can use the Intuos2 or Intuos3 tablets on it, with CS and Corel; with decent performance on your configuration.
Other (important) PPC programmes:
10.4 Server Admin Tools
After Effects 6/6.5
Alien Skin (PS Plugin Series)
Appleworks 6
Art Director's Toolkit 3/4
Carbon Copy Cloner 2.1.1/3.x
Chicken of the VNC
Coda
DivX Doctor
DivX Encoder
Dock Tools
DomainBrain
DVD2oneX2
Final Draft 7
Firecracker
Firefox
FontDoctor X
Framemaker 7
gRphic Converter
GURU
Handbrake
HexEdit
iCab 4
ICQ
iDVD
iGetter
iLinkPod
Image Capture
iSquint
iSwipe
iTunes 3/4 (Internet/WAN streaming)
iTunes 6/7
JFuse
Lightwave
Lightwave 3D
Mac the Ripper
MacAmp
MacPorts
Macromedia Dreamwaver 2004
Macromedia Flash 8
Melody Assistant X
MenuMeters
NetFinder
Office 2004
OpenDNS Updater
OSXVnc
Pandora
Pic2Icon
Process Wizard
Quickbooks 6
RAGE Webtools
Roxio Toast 6/7/8
SANE (SANE/TWAIN Scanner Bridge)
SideTrack (for laptops)
Suitcase Fusion (a font management system from Extensis)
SWF Player
Tabmeister
TechTool Pro 4
Tinkertool
Tomeviewer
UnRAR X
Virtual PC 6/7
VLC 0.8.6 / 0.9.2
Whois Analyser Pro
Windows Media Player