To program a current series of GE PLC (90-30, Micro, Versamax, 90-70, RX3i, RX7i), you will need GE's Proficy Machine Edition programming software.  It is currently at version 5.8.   The name of the software changed from Cimplicity Machine Edition to Proficy Machine Edition at version 5.0, so this makes it confusing, since GE also has a SCADA software package called 'Cimplicity'. 

If you are still using GE's DOS-based programming software, Logicmaster, you can import your program fairly seamlessly with Proficy.  You can also import programs from Versapro, which was GE's first attempt at a 32-bit Windows-based PLC software, but was very buggy and almost unusable.

Cheers!

You will have to contact your local representative to see if you can obtain a copy from them.  You can find your local rep on the ge website:  http://www.ge-ip.com/