I upgraded the memory in my Acer Aspire Revo yesterday.  I had to follow a video on Youtube to be able to pry open the case.  With the cover finally off, things went much easier.  I ordered the memory from Crucial Technology.  Their part number CT1161615 is a bundle of two 2GB 200 pin DDR2 SODIMM Unbuffered PC2-6400 800 MHz 1.8V 256 Meg x 64 Class 6 memory.  Once the memory was installed, putting the case back together again went much better than taking it off.

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Booting up Windows 7 and checking the memory revealed that 3GB (out of 4GB) is now available instead of just 1GB (out of 2GB).