It's not possible to read that event log in any practical way.
Go to Control Panel > Performance Information and Tools > Advanced and look at the Reliability index for any flagged problems there.
If something is consistently affecting boot times, it should noted there.
There is also a special section of the Event Viewer related to boot times >>
Application and Service Logs > Microsoft > Windows > Diagnostic Performance.
http://blogs.zdnet.com/Bott/?p=246
Try testing with Clean Boot Troubleshooting techniques >>
Run
msconfig and select the "Services" tab.
Check "Hide Microsoft Services" and then disable the rest. Also uncheck "load startup group" on the general page.
See one or both of these links for detailed information. The second is for Vista -- but it is actually the best written and applies equally.
http://support.microsoft.com/kb/929135
Now restart and test the issue at hand
If no problems, run
msconfig and recheck half the disabled items on the Services tab. Test again. If the problem recurs, UNcheck half the items you just checked to narrow down the culprit.
If the problem didn't occur, check the other half, so all the Services are enabled -- proceed to do this on the startup tab as well.
Get the idea? You want to isolate the problem to a specific startup if possible.
Note: if you already have items unchecked under msconfig > startups and are in “selective” startup mode – you should note what these are before beginning. They will need to be de-selected again.