Chrisd... I have CS5 Extended V12.1. I will try Picture Window Pro, thanks.
Wishgranter... It seems that I have the 64bit version with a 64bit OS and I have 32GB of ram. Is there a setting in photoshop that I can change? I am a novice at Photoshop! I am only using it to open the ortho's to edit them; brightness, contract, add text etc.
Adobe Photoshop Version: 12.1 (12.1x20110328 [20110328.r.145 2011/03/28:10:30:00 cutoff; r branch]) x64
Operating System: Windows 7 64-bit
Version: 6.1 Service Pack 1
System architecture: Intel CPU Family:6, Model:10, Stepping:9 with MMX, SSE Integer, SSE FP, SSE2, SSE3, SSE4.1, SSE4.2
Physical processor count: 8
Processor speed: 3192 MHz
Built-in memory: 32656 MB
Free memory: 28575 MB
Memory available to Photoshop: 29624 MB
Memory used by Photoshop: 60 %