Hi,

I confirm that GNS3 is working perfectly under Windows 8.1 in version 0.8.7 and 1 beta 2/3.
I would recommend to keep the version 0.8.7 if you need stability and to be full operational (from what I've seen the beta doesn't yet integrate every functionality, even if it's the one I'm using the most).

For the IOS files, they are not provided with GNS3, as Juniper files. Be careful, every routers aren't supported by GNS3, check which ones fit your needs (switchs aren't supported, you can emulate some switch functions thanks to slots you use on routers).

I recommend you to upgrade your Windows 8 to Windows 8.1 update 1 to have every security patch from Microsoft, and to be sure to have a full programs compatibility. Almost no one program any longer for Windows 8, but directly for Windows 8.1. Some will work, some will not.

I hope this can help you,

B.R.

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New to GNS3 / working on network design mainly
Running : GNS3 1.0beta3 All-in-One / Wireshark 1.12.1 / VirtualBox 4.3.16 / Widows 8.1 and 10 / T430s 8GB RAM
Sorry for my poor English level