mysql versions

[Me - Atlantic]

I currently have the (default) 4.0 mysql server and clients installed,
and noticed that synaptic contains version 4.1 of both the server and
client binaries.  Can I install 4.1 over the 4.0 version, or do I need
to remove the 4.0 server and clients and install 4.1?
(I have vpop and iptables interfaces which have databases in my current
server).

Running 5.10 / 2.6.12-10