PowerPC problem solved.
After installing lion, PowerPC dependant programs would not run due to the lack of support for 'Rosetta' meaning I couldn't open my account software.
I have now connected a external drive and installed Snow Leopard on to that. Booting from this drives enables me to run the account program from the internal hard drive though 'Finder" without having to copy or reinstall the software on the external drive. well happy.
At the end of this tax year I will install a new accounting software from someone that's supports Lion.
iMac 27" aluminium, iPhone 4 & iPad, Mac OS X (10.6.4)