How to Resolve - Acer laptop running Windows 7 shows "2.93 GB useable" but has 4GB installed?

Acer laptop running Windows 7 shows "2.93 GB useable" but has 4GB installed

Since having to reinstall windows 7 64-bit (as microsoft released an update that made my computer unbootable!), I have had trouble getting my computer back to how it was.
(Couldn't get [Solved] How do you do a image recovery? empowering technology to work on my acer laptop, or some of the drivers).
The main problem is Is there an easy way to copy and paste text from an excel spreadsheet or word document to fill in work history forms when I am applying for jobs online? that I cannot use all 4gb ram installed, it says "2.93 GB useable".
Before reinstalling windows 7 64-bit I could use the full 4gb ram.
What can I do to be able to use this ram again?
*original title - why can't I use all ram*

Keys to the Problem Acer laptop running Windows 7 shows "2.93 GB useable" but has 4GB installed

And what update would Any time I am downloading data, my mouse lags significantly. The solutions I have found on forums (disabling real-time malware scans, updating drivers, etc.) don't work. Help? that have been?
Where are you seing 'useable'?
If you have driver / other problems then these need to be fixed first
http://support.acer-euro.com/empowering_technology/#ETN

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