The easiest and cheapest way would be to put a snow leapard partition on the mac. and run the old quicken and quickbooks on that.
quicken for sure wont run under lion and there is no upgrade path from 2004 to the 2007 or essentials that will*. You would have to purchase 2005 ( its available on amazon or ebay most days but it cost more than the 2007 ) and go through that.
the quickbooks you could probably convert if it will export a portable file that can be read easily. I would have to really check on exactly how to do it otherwise. is that pro 5 or 2005 ? I looked it up and i think the quickbooks will read and convert the old file directly This is what it said exactly
. For Mac: QuickBooks 2010 for Mac can upgrade files from QuickBooks Simple Start, Pro, Premier, and Premier Accountant Edition 2008, 2009, and 2010 for Windows; New User Edition 5.0, 6.0, 2005, and 2006; and QuickBooks Pro for Mac 4.0 (M12), 5.0, 6.0, 2005, 2006, 2007 and 2009 (U.S. versions).
* from quicken support http://quicken.intuit.com/support/help/lion-compatible-quicken-mac-2007/GEN83769.html
File conversion is not possible for Quicken 2004 for Mac and prior versions. File conversion is only possible for Quicken for Mac 2005, 2006, 2007, and transactional import for Quicken Essentials for Mac.
If you want to consider a snow leapard partition and keeping the old versions ( it doesnt really solve the problem in the long run but you dont have to worry about it for awhile and its cheap and easy and you dont have to learn the new versions either. )
1. In Lion applications go to utilities / Disk utilities2. In the top left click on your main disk drive and there will be a "partition" option on the menu on the right3. click on + on the lower corner to add a partition4. give it a name and select the size. It should be at least 10 gb as snow leapard takes 6 itself and you need room for applications and data5. put your original snow leapard cd in the drive and reboot the computer. It will boot from the cd and ask where you want to install the snow leapard. Select the new partition that you just made6. Once that is complete you can remove the disk and reboot the computer and it will ask you which partition you want to boot from whenever you restart the computer.7. Boot into the snow leapard partition and install the old quicken / quickbooks