how can i install windows installer 4.5 on a Vmware

I am installing Exchange server 2007 on a VM workstation running windows server 2008, one of the prerequisites is windows installer 4.5. I downloaded it from Microsoft site, but when installing, it returned the error “not enough memory to install the software” the Vm workstation has over 12G disk space and runs on 512 MB of RAM, and the installer is just 2.92MB. Pls can someone tell me how to go about it