Can't load IA 32-bit .dll on a AMD 64-bit platform
Yes, you'll have to recompile the DLL for 64-bit. Your only other option is to switch to a 32-bit JVM, or otherwise get some 32-bit process to load the DLL on your behalf and communicate with that process somehow.
I had the same issue with a Java application using tibco dll originally intended to run on Win XP. To get it to work on Windows 7, I made the application point to 32-bit JRE. Waiting to see if there is another solution.
Short answer to first question: yes.
Longer answer: maybe; it depends on whether the build process for SVMLight behaves itself on 64-bit windows.
Final note: that call to System.loadLibrary is silly. Either call System.load with a full pathname or let it search java.library.path.