Increase RAM From 4 GB to 8GB on Aspire M5630 Desktop?

The listed maximum amount of RAM the Aspire M5630 can support is 4 GB, so when I bought my M5630 I immediately upgraded to 4 GB so I could use the 64-bit versions of Windows.  That was fine for Win VISTA, but for Win 7 and 8, more is better.  I know there are 8 GB RAM kits (2 x 4 GB) for DDR2 800MHz memory out there, which would help prolong the lifetime of my computer.  Is there a BIOS upgrade that can allow the M5630 to see 8 GB, or is this a hardware limitation rather than a BIOS limitation? 

I'd like to squeeze the last drop of usefulness out of this computer, but even after upgrading the video card and having cable internet service, I think some websites (especially multimedia) are starting to render this desktop if not obsolete, at least it's falling behind the power curve.  For $100 to $150 this would be a low-cost way to keep up with the cyber-Joneses.  If I can't boost the RAM, then I'll just have to suck it up and look at buying a new computer with an i5/i7 processor and 8-16 GB RAM.