ok - first of all, Oracle Support still has SP24 out as an active piece of software. However, like ALL the software, you can only download Oracle software if you have an active maintenance agreement with Oracle. Asking if people/companies can provide "other ways to obtain the software" is going to get you in a LOT of trouble. SP24 is available on the Knowledge Garden - if you have maintenance, then you're entitled to download it. If not, then you made a conscientious decision to stay with the software that you already have, and deal with the consequences when operating systems and hardware come to end-of-life.
So, given your predicament - you can either attempt to upgrade your windows OS and hope that your service pack works on it - or stay with Windows 2003 for as long as you are running EnterpriseOne.
If, on the other hand, you DO have a maintenance agreement with Oracle - then you should absolutely get on the phone with them and see why you can't seem to download SP24....