Want to upgrade Memory

I am running an Inspiron E1705 MP061 A00 9400 with Win 7 and have been for several years.  It's just slightly slow.  I have run the full Dell diagnostic and all passed with flying colors.  I was instructed to upgrade the BIOS before installing a 2nd GB of memory (replacing the old 1GB stick with 2 - 1GB sticks).  I have run across comments that the PC shouldn't be able to run Win7.  I have not been able to find any info on upgrading the BIOS for this PC.  Where do I go?  DELL Support reports 0 results.

BIOS Vendor: DELL,  Release Date 12/17/2005,  BIOS Ver A00, ROM SizeL 576kB

Please Help...I LOVE MY DELL!