Monitoring local network performance over time

I'm interested in tracking local network performance to have information for those situations where people say things like the software is slow lately.

Is testing periodically how long it takes to upload and download a file over the local network and storing the data in a central database
a valid way of keeping tabs on network performance from clients to a server?

I vaguely know about iperf but this is something I could implement easily because I already have a central database and a shared folder on the server and software on each machine that could easily be altered to accommodate this.

So if a small file was uploaded and downloaded every n seconds and then the time taken for each stored in a table with columns like
datetime, computername, filesize, upload time, upload speed, download time, download speed.

Is this too simplistic?
Are there other things I could easily monitor in vb6, ping response times, total network traffic from a particular machine.
I am asking from a position of ignorance really, as may be obvious!