The only time I have every seen this to be "true" was the special case of poorly written wireless network adapters that required a service entry, which is something a limited user by default cannot make.
Update the NIC drivers, as there should not be a necessity for Admin rights for local users to gain network access with a properly written driver for XP.
As a workaround, (if yours is a wireless/service case) launch the wireless client through Scheduled Tasks, the schedule being 'at Startup' or through Group Policy scripting for the Startup script. In this instance the service entry would be made under the permissions of SYSTEM and would succeed. The user could remain a limited user.