Network monitoring tool

I’m looking for input on network monitoring/server monitoring type tools. Originally we were looking at GFI events manager for event log consolidation of servers and PCs. But at this time we’re looking at something that will bring in our routing, switching, access points and servers as well. The Cisco CS-MARS device is looking promising, but may be a little out of our organization’s budget, so I was wondering what other software or appliances everyone has experience with.