HP SIM is free too, just download it from the HP site. Only limitations are if you need to go for a SQL backend (oracle in our case). But for you install an MSDE instance should be fine. The chargable items are the extras like performance pack and a variety of others etc. Storage Essentials on so on.
HP SIM is up to version 5 SP 2 I think. I've install HP SIM on DL360, DL380, ML370s and Optiplex desktops for the small installs. Windows 2003, HP SIM from HP's site and you should be away. Just a case of setting things like SNMP community stings etc.
The version control agent is very cool as well.
I'm installing it on a new DL385 with 12GB RAM tomorrow, and we may increase the RAM further. Reason for so much is that it's going to have storage essentials on it too as we've got about 10 EVAs and a few XP Arrays (I'm not part of that team

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Snow Munki, where are you based?
How have you built the servers you are trying to monitor, via smartstart? Is SNMP installed etc.
Post a screen shot of the SNMP settings you got under services.
http://h18002.www1.hp.com/products/servers/management/hpsim/index.html
The free stuff you'll deffo get with the server is the proliant support pack.
After HP SIM, next task will be to moan enough for them to get ride of the sh1te lotus notes and bring in Microsoft Exchange. IBM - you suck!