If it were me, I'd just cut my losses and run at this point. You're already out the cost of the printer, no point adding to that the cost of an OS upgrade. But if you haven't opened the ink carts, you could probably return those for a refund if it was fairly recently that you purchased them. Otherwise, there's always ebay or craigslist.
Last June I purchased an HP OfficeJet Pro 8500 all-in-one with a 2-year extra Office Depot warranty to run with my HP XP Media Center 2002 system. I was told that if I had any problems, just to call the number on the O.D. warranty papers.
Since the time I bought it, I've had endless problems connecting with it. First, my computer would simply stop its connection with a printer - usually when I was printing PDF files from on-line sources. I could only get it to run again when I would turn off and reboot my computer.
I called the magic O.D. warranty # but I was told since I was on HP's warranty I'd have to go through HP. Since then I have been talking with 8 HP IT people from all over the world, each one who promised me they would fix the problem. Midway in our chat, usually after the techie had exhausted his possibilities, I would mysteriously get disconnected - always before they had given me a "ticket" number to log in the event. The last IT person said that mine was one of the rare cases where I needed to purchase Windows 7 in order to get the system to work. I went ahead and ordered it because they told me I could get a 10% discount and they said I could always return it without problems. Office Depot said they could do a lot better than their price.
In reflecting about the pros and the cons of stripping out my XP Media Center system with Windows 7, I'm wondering:
1. If I did this, would all or most of my present programs still work?
2. What other problems might I face in upgrading?
3. Would Windows 7 in fact work with the printer? (Note: I've recently spent $130 for new ink for this printer, which actually does copy. If I insist on a computer exchange, would I lose all the $$ I just spent for 940 XL cartridges?)
4. I'm a bit of a techie, would it be a royal pain in the rear to strip out XP and install W 7?