Maximum rows in SQL Server Express 2008 / schema recommendations

I have a c# windows application which tracks the time it takes to assemble widgets on a production line.  The line is given a job to do which specifies which widget and how many to assemble.  The job completed by one or more assembly sessions.  The job being closed when the final session completes the last widget. For each session the average number of seconds to complete a widget is stored.    So I have a table Job and associated table Session.

The customer wants more granularity.  Instead of the average seconds per session they want to know by hour so they can compare the average time from 8:30 to 9:30 Monday to the same time on Tuesday.

To give them the ultimate granularity I am considering creating a table Assembled with the fields SessionID, CompletetionDateTime and Seconds.  With up to ten jobs running simultaneously and each job completing up to 1000  units a day this could result in 10,000 rows created daily.  Should this be a concern?  Each row will be small but I am concerned about performance impact etc.

Grateful for any input!