Is This Worth Upgrading

Hi

My Tower is a good few years old now and with the support for XP stopping I'm wondering if it's worth getting some more memory for this and windows 7 or biting the bullet and investing in a new tower. Also an idea of how much memory I could add along with cost would be a help.

As it stands......HP Intel Pentium 4 CPU 3.20GHz 1.00GB Ram. Windows XP

Thanks