I have mercury 845gl intel chipset motherboard in my pc with 40gb HDD ,128mb DDR RAM ,intel celeron 1.7GHz Processor .Now i want to upgrade my pc without changing Motherboard and processor
What's the maximum amount of RAM(capacity in GB) and HDD(capacity in GB) i can attach to it?
and which one(ddr/ddr1/ddr2)

Go to www.crucial.com and use their onsite diagnostics for your ram.
Mercury put out several boards based on the Intel 845GL chipset...we'd need to know the exact model number to help you choose the correct RAM. Try the Crucial scanner as was suggested by grasshopper.
