I am a recent convert from Spiceworks, I needed something a little more fleshed out (or so I thought) I purchased Desktop Central and Service Desk Plus.
On Spiceworks, I would get emailed an alert if a hard drive was filling up or a toner cartridge was about empty. I went to set this up in ManageEngine and couldn't find a place to do it. I contacted support and they told me that neither of these applications have that capability and that I would have to buy Opsmanager to get that functionality.
SDP and Desktop central have the information, you can click on the asset and it will show you that a hard drive is about full.
But it won't send me an alert? Without buying software I don't really need? That seems wrong and crazy.