VMWare's vSphere console and Veeam's monitoring utilities do an admirable job of showing admins various statistics on CPU usage, memory usage, percent utilization, etc. of VM's and the hypervisor host.
Is there a similar solution or series of solutions for monitoring a Xen server visually? Monitoring the status of VM's, their resource usage...etc...or is it mainly having to install agents on the virtualized guests and centralize it that way?
I can only speak for Citrix XenServer 5.5 and XenCenter. They come bundled with monitoring tools for free but are severely hamstrung in terms of data retention. Probably something you have to buy to obtain access to.
There's a nice dashboard control panel for XenCenter to see the general usage of resources for all VMs but yes, you have to install XenTools on the guests to view those metrics in real time. In comparison to VMWare or Veeam, it's probably just good enough. I have no exposure to vSphere or Veeam so whether to say they're similar I can't speak to.
There are no Xen specific MIBs available, not even for the Citrix version. As already stated you can use XenServer and use the nice gui management tools. The only other way to go is to parse the output of
(or the 'xe' equivalent on XenServer) every five minutes and feed that into your graphing tool of choice.
I've never felt the need to use a solution specific to Xen for visualizing these stats. You can select the generic monitoring system of your choice (Cacti, Zabbix, Zenoss, OpenNMS) and install an SNMP daemon on your VMs. For me this is the preferred approach as it does not propagate the use of even more monitoring tools on our network.
You can use collectd - http://collectd.org/ - to get the data you want. It uses libvirt to monitor performance data and therefore could also be used with KVM and other hypervisors. This will not be as polished as Veeam though and note that it uses RRD files and therefore historical data is stored in a "lossy" way.