There are a great number of tweaks you should do. You're computer is old, but with a little magic, it should run faster than it does now.
1. Open internet explorer, and under the Tools menu, click Internet Options. Then click the settings button (under temporary internet files), and drag the slider to a value below 60.
2. Download this program to save some disk space http://downloads.stevengould.org/cleanup/C.../CleanUp312.exe
3. Download Ad-aware, and scan your PC for junk files: http://www.lavasoftusa.com/software/adaware/
4. Download Spybot to remove the Wild Tangent spyware: http://download.com.com/3000-8022-10289035...tml?tag=lst-0-1
5. After you fixed these problems, scan again, and post a new score.
I think the fix for the red flag in security is easy enough to follow, but someone will probably post better instructions than I have. Hopefully I have helped.
Some people will post more tips, so fix as much as possible before scanning again.