One possible solution is to use QuickTransit from Transitive, which allows SPARC binaries to execute on Solaris/x86, Linux/x86 or Linux/Itanium systems. It can be downloaded from the Transitive Web site at: http://www.transitive.com/evaluate. Unfortunately, IBM has acquired Transitive and is no longer selling Transitive, instead integrating it into their PowerVM product. Whether Transitive will be available as a stand-alone emulator in the future or not is yet to be seen.
Another option is QEMU. QEMU supports several SPARC plaforms and is capable of booting operating systems NetBSD for example which still actively supports both 32 bit and 64 SPARC. Sources for QEMU can be found at the QEMU wiki: http://wiki.qemu.org/Main_Page. Or install it via your native packaging system precompiled binaries of recent versions of QEMU are available for windows at this site: http://lassauge.free.fr/qemu/.