Hi Raghuram,
As Yves and D. Valliant have mentioned you have option of SM19/SM20 Audit log, ST03 or ST03N. I think your requirement is pretty simple and you should go ahead with ST03N.
ST03N>WorkLoad>Total : Data is stored as Day/Week/Month. Once you select the month: Then under Analysis Views>Transaction Profile>Standard. Here you can sort the Data for only SE38 & SE80. You can enhance your analysis here by double clicking the tcodes which will give you the list of users who have executed that transaction. Please be aware that the data is stored by Day then by Week & then by Month (I know it is little confusing but Basis person can show you what it means) so Month data may not include the current Day Data so you will have to collect all the data and tally it separately.
Audit Log is a nice set up but it still config change which may need additional development, testing of filters and transports where as ST03N will give you all you are looking for in a very short time and concise manner.
Regards,
Shivraj Singh