Is there an alternative to Cacti that is Windows-only?

I just setup Cacti a few weeks ago on Windows. I found this post on the Cacti forums. It is basically a prepackaged installer for Windows. It will use IIS if you have it installed, or it will automatically install and configure Apache if you don't. It also installs all the prerequisites that you probably don't want to deal with either.

It was VERY fast and easy. Setting up the SNMP queries took longer to get correct than installation.

It seems to be working fine. I installed it on Windows 2008R2 Datacenter Edition and didn't run into any problems or "gotchas".

The only thing I did need to remember was to give the account that runs the scheduled task "Logon as Batch Job" permissions. (It runs every 5 minutes to repoll your SNMP queries. I'm sure this is configurable, but it is more than sufficient for my needs.)

If you only want to monitor Windows servers, you could try the built-in Windows Performance Monitor. It has capability to log some data objects you define from the server or other servers in the same domain. It could be accessed via 'My Computer', right click, choose 'Manage', 'Performance Logs and Alerts', then 'Counter logs'. See http://www.windowsnetworking.com/articles_tutorials/Windows_2003_Performance_Monitor.html