I think the amount of scrolling is not bad at all. Many other sites have as much or more. For example, see
http://www.pcmag.com/ and
http://www.extremetech.com/.
I would get rid of the borderlines around the table cells. As you know, tables are commonly used to create columns in page layout but many sites make the table cell borderlines invisible. In my opinion, it gives a more sophisticated look. The two sites mentioned above are examples. I could cite many others.
Along with this, the use of different colors for table cells could be elmininated or decreased, with a white background being used more often. Again, the two sites mentioned above are examples and I could cite many others.
The font size could also be smaller. This might create the opportunity to add a fourth column, perhaps with some banner ads in the right column.
And, regarding ads, I would not begrudge a little more commercial look. The development of all the content in ComputerHope.com must have been a huge undertaking. You're entitled to make some money with this site.
Regarding page width, you could perhaps set it wider, somewhere between 800 and 1024. I believe a the percentage of users now using 800x600 resolution is rather small.