I have three related questions.  Can you add DDR Ram memory to an existing SD Ram?  Is this something the average user can do by themselve?  Is $10.00 a good price for 256MB of Kingston DDR Ram?

Dimension 4300, P4 at 1.6 GHz.

128MB SDRAM at 133 MHz

16MB ATI Rage Ultra 4x AGP

40GB, ATA-100,7200 RPM Hard Drive