Installation will fail under windows 7 or vista if you are not running under an administrator account.
For best installs, disable Windows User Account Control, and temporarily disable Firewalls/Security Softwares while installing or patching games/clients.
^_^ I installed without a hiccup
after you install Shaiya, you can remove the ignite & akamai programs, if you no longer wish for them to remain on your machine, and shaiya will work just fine