Hi there, i have an old Graphite iMac G3 600MHz with 256MB RAM and is planning to upgrade it to 1GB. I know the imac is compatible with both PC100 & PC133 SDRAM. What I wanna know is whether it uses high-density or low-density DIMMS? Anyone can shed some light on this for me? And one more thing....where can i get Mac OS X 10.3 on CDs? My iMac only has a CD-RW drive unfortunately...and the installation discs i have are DVDs.