I'm not sure how much difference there is, probably little. However, to install the RC2 version, you'd have to use a registry tweak which is included. Plus, the download link to RC2 is taken off, since it is officially superseded by the final one. So instead of going through all that, just download the final version
Note, SP1 must be installed before installing this service pack. SP2 doesnt seem to be required, but it is HIGHLY recommended.
Have any of you had any trouble? Installation went smoothly, though I recommend you to close all programs first (disconnect from web, close firewall/antivirus/etc) and run a registry backup. However, I had this brief error message on two windows of command prompts when I restarted. Wonder why.
Installed it on my laptop as well without problems (no messages too). The laptop has a partition with a clean install of Windows XP SP2 with laptop drivers. Plan to do an image backup of it soon.