2.2.20-1.w5 installed, it is looking specifically for
2.2.3-65.el5 as shown by the
=. It also seems that you have a nonstandard package installed - i.e. one that did not come out of the standard repos since all of the RH/CentOS packages end in
.elX where X is the major version number.
To Answer the question in the comments. It appears that the
.w5 suffix is from the Webtactic repositories. If you don't need anything from that repo, I would suggest removing it's entry in
/etc/yum.repos.d after removing the Apache install. If you do need things from that repo, I would suggest following their instructions at the bottom of the page I linked to above to disable the repo and only use it when needed.
There is no way to change the version of Apache that is installed without downtime, although if you backup the configs first it should be very minimal - on the order of 5 mins tops.