Any thought about how to install Windows inside Linux Lite?

[Moltke]

is there a way I can install windows in it aside Linuxlite

Yes, you can dual boot or run Windows inside a VM in virtualbox.

I need windows to run an app I need in work

May I ask what app are you trying to run? Because honestly, with only 1gb of RAM Windows 7 won't run as desired. I'm dual booting Windows 7 and LL - although I'm actually using LL on a daily basis and haven't booted into Windows for over 2 months I think. If the app is supported on Windows XP you might want to try running XP in virtualbox instead, it'll only need around 512gb. However, if I were you I'd consider adding up at least 1gb of RAM. 
Depending on the app you want to use, you could also try ReactOS in VirtualBox, which as read on its website "Imagine running your favorite Windows applications and drivers in an open-source environment you can trust. That's ReactOS. Not just an Open but also a Free operating system."

the spec of his CPU would exclude the possibility of win7 in a virtual machine.
The CPU needs to be hyperthreaded, and have 4-cores instead of 2; the T7400 has neither.

You'll have to check whether it is possible or not for your machine to run either Win 7 or XP.

Hope this helps!