Hi there,
What is the video card in your Dell 1525?
There are several postings of Win-7 successfully running on a 1525, using needed Vista drivers.
I ran the Win-7 Upgrade Advisor on a 1525 with Win-XP, thinking about upgrading, and it said it was not completely compatable.
Might check on the Dell website and see if they have a Windows 7 driver for your video card.