If you are ready to make the switch to Windows 10, please make sure your software is fully compatible with the upgrade. Some software has been known to cause issues when upgrading to Windows 10, leading to a computer that is not fully usable.
The Cisco VPN Client Version 5 is NOT compatible, and will cause all network connections to be unusable and possibly irreparable, requiring a reinstall of Windows.
The safest option when upgrading is to remove any programs you do not need before the upgrade, and reinstall them after the upgrade. Programs which may be best to remove through the upgrade are Antivirus software, and system plugins such as VPN connections or system tweak utilities. If a program changes the core OS in a way that is not fully supported, corruption is possible during the upgrade.