I decided one day to try out Aperture 2 and found that it won't run on machines with less than 1 GB of RAM. Tinkering around, I stumbled onto some files that can fix this.
First you need Aperture 2 or the trial version from Apple. Once you have it, you need to drag the Aperture package and packages folder to the Desktop. Right-click the package and choose Show Package Contents. Open Contents and right-click Aperture (trial).dist; choose Open With and then Other. In the window that displays, choose TextEdit (or your favorite text editor) and scroll all the way to the bottom of the window. Now slowly scroll back up untill you see:
function checkRAMRequirement(RAM)
var requiredRAM = (RAM * 1012 * 1012);
var actualRAM = system.sysctl('hw.memsize');
Change the required RAM to:
function checkRAMRequirement(RAM)
var requiredRAM = (RAM * 256 * 256);
var actualRAM = system.sysctl('hw.memsize');
Save the file and close it. Double-click the Aperture package on the Desktop and follow the instructions to install the program.
<key>AELMinimumRAMSize</key>
<dict>
<key>block</key>
<string>1000</string>
</dict>
To this:
<key>AELMinimumRAMSize</key>
<dict>
<key>block</key>
<string>256</string>
</dict>
Save the file then you'll be able to launch Aperture if you have less than 1 GB of RAM.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20080811074247270