Nomen, you can use a different CD set, but in your case it must be an OEM version of XP. OEM keys don't work with retail CD sets or volume license versions.
For legal reasons, you must also make sure that it is the same language version of XP that you originally used. You would also not be allowed to install a multi-lingual version of XP unless you own a license vor that. And probably it would require yet another CD key than the other versions.
If your last activation was more than 30 days ago, the new activation should work over the Internet without having to give Microsoft a phone call.
For legal reasons, you must also make sure that it is the same language version of XP that you originally used. You would also not be allowed to install a multi-lingual version of XP unless you own a license vor that. And probably it would require yet another CD key than the other versions.
If your last activation was more than 30 days ago, the new activation should work over the Internet without having to give Microsoft a phone call.