Team Fortress 2 Forum

Model Name: iMac
Model Identifier: iMac5,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 4 MB
Memory: 1 GB
Bus Speed: 667 MHz

ATI Radeon X1600:

Chipset Model: ATY,RadeonX1600
Type: Display
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 128 MB
Vendor: ATI (0x1002)
Device ID: 0x71c5
Revision ID: 0x0000
ROM Revision: 113-xxxxxx-139
EFI Driver Version: 01.00.139
Displays:
iMac:
Display Type: LCD
Resolution: 1440 x 900
Depth: 32-bit Color
Built-In: Yes
Core Image: Hardware Accelerated
Main Display: Yes
Mirror: Off
Online: Yes
Quartz Extreme: Supported

??!

I don't see any issues, I have the same mac. To be sure, you can just download our demo and give it a try without any risk. I think there is a TF2 demo as well, if you do not have the game yet.