These versions of software and firmware should work together properly. RSLinx 2.59 is the current release as of now (July 2012) and although RSLogix 500 version 7.30 was released in September of 2007, that was the version that supported SLC-5/05 firmware FRN 10.
The "Unrecognized Device" error in the RSWho browse is related to EDS files registered on the computer. In theory, version 2.59 of RSLinx Classic should have installed all the past and current EDS files for SLC-5/05 controllers, but it's possible that you skipped that section.
Is the "Unrecognized Device" a question mark with a red X, or just a yellow question mark ?
Are you using the "Ethernet Devices" driver, or the "EtherNet/IP" driver ?
The red X indicates that there's no response from the SLC at all, while the yellow question mark indicates that the device has responded but that RSLinx could not find a corresponding EDS file.
You can download EDS files from the RA server and register them using the RSLinx Hardware Installation Tool (under the Rockwell Software menu in RSLinx Classic -> Tools (or some similar path, I don't have my programming PC handy).
http://www.rockwellautomation.com/resources/eds/