Not with any native XP tools.
I caution you even trying this with third-party tools. The issue is not whether they can do a logical join of the partitions, they most certainly can.
The issue is that XP system is setup on the second partition. When you join the partitions you will end up -- if you do end up there successfully -- with XP and its thousands of registry entries and the BOOT.INI file pointing to a non-existent drive letter/partition.
There is only one sane way to do this: backup your data and settings to another drive or to removable media. Boot from a Win98SE floppy or use the web site of the drive manufacturer to download their setup utility. You need to use FDISK or another tool to remove all existing partitions, (essentially erasing the drive).
Then boot from the XP CD and let it create a single NTFS partition for the entire drive, install XP, and you can then begin re-adding your software and restoring your data.
You might find the Files and Settings Transfer Wizard, or its big cousin, the User State Migration Tool of use:
You must treat this as a clean installation situation. There are no effective shortcuts to the issues posed by your XP system being installed on the second partition currently.
Personally, I would leave matters alone.