How can I perform the install and avoid this problem.
In short, you can't. Redmond code will overwrite the MBR.
Once XP is installed, you will have to re-install grub. Here is a link to one How-to.
Another option would be to install XP as a virtual machine. This is how I run XP. There are several 'virtual machine' systems. I use VirtualBox from Oracle. XP runs better in v-box then when its installed as a stand alone system. I don't do gaming, so if the install is for games, your best bet may still be a dual boot option.