We have 300 windows xp machines on cruddy old hardware across the company.

With extended support for XP ending April next year we're looking into our options.

Couple of options:

1. Replace the 300 PC's with full windows 7 PC's (£100k +?) - no use of terminal server (our current model)
2. Replace the 300 PC's with off the shelf thin clients & make use of our terminal server - Cheaper clients but Terminal Server CALS required?
3. Keep the 300 PC's, replace windows XP with linux thin client capable of connecting to our terminal server - no hardware costs, just Terminal Server CALS required?
4. Keep the 300 PC's - remove hard drives and make use of a PXE bootable "thin client" to connect to our terminal server

If we were to choose option 4, what our the options out there? Is there any official PXE bootable thin clients for terminal server out there? If so, what are the licence requirements?

Is there options we haven’t considered? There must be lots of companies out there in this situation - curious what the current trend is for this problem?

Edit: Option 5 - Create a bootable Windows PE image with RDP auto start and use that as a "thin client" for our terminal server - is Windows PE licence free in such a model?