Tips on using Excel:
TIP 1:
Make sure that when you import the log into Excel you tell Excel that it is delimited by commas. If Excel doesn't automatically open the "Convert Text to Columns Wizard" when you open the file, you can open it manually by selecting all of column A, clicking the Data tab (assuming Excel 2007), and choosing Text to Columns. At that point, put a dot in Delimited, click Next, remove all checkmarks, put a checkmark in Comma, and click Finish. You can then adjust the width of the columns to fit your needs.
Once this is done, highlight your entire TABLE (not the entire spreadsheet, just the data in the table). Go to Home and click Format as Table. Select any preset table (depending on your color preferences). Leave the checkmark in My table has headers and click OK. Your data will now be a table and you can easily filter it by clicking on the filter button next to each header.
TIP 2:
If you want to get a list of what computers experienced a particular detection, you really need to learn how to use Excel's Pivot Table feature. It is EXTREMELY powerful and would easily merit a half-hour or learning how to use it. (You will probably end up using it for more than just SEP logs.) I recommend a video tutorial. This one may very well work: http://www.youtube.com/watch?v=7zHLnUCtfUk
Regards,
James