Even easier -- In RSLogix5k, Tools > Translate PLC5/SLC. It will then ask you for the SLC program file and a destination file to store it to, some configuration stuff, then *poof* does it.
BUT -- It will NOT be a nice translation. You will still need to assign tags to your physical I/O. Plus the "addresses" will still look like SLC addresses, and will NOT take advantage of the 5000 matrix style. Plus, there may be a few things that won't convert nicely (like SCP... maybe someday they'll add that command to 5k ladder...)