Hi Natacuk,
Yes, running Windows 7 Pro x64.
I was a little cautious when first buying the Ram, as you know, DDR2 is getting expensive now. I was a little worried in case it wouldn't work. But worked fine, so I'm assuming it only says 4GB in the Dell manual just because it's outdated documentation?
Really needed 8GB as I run a few VM's on my system too.
Even though the System was built in 2006, it's still running really well. The only thing I've had to replace was the DVD drive a few years ago.