I think you still have time to weigh the pros/cons as the 25th is a little bit away.
I understand you don't want to let down the company but really you have to do what's best for you because trust me the company will always do what's best for them.
Still, you don't want to be unprofessional or burn bridges so let's think about this.
You go on the interview and you don't get the job- you are safe.
You go on the interview and you do get the job- you have to make a choice.
If it were me and I REALLY, REALLY wanted the other job I'd go on the interview and hope to hear back soon. Then I'd let the other company know ASAP. I wouldn't wait until the last minute to tell them, but I also wouldn't cancel the gig if I was uncertain if I was going to get the other one.
At my hubby's job they are opening a new location in NY. A manager was set to move to NY and they hired all these people, etc. A FEW DAYS before everything was supposed to happen, the manager quit and moved to TX because he got a better offer. Just like that, bam, gone. So it does happen but I say in order to display the utmost professionalism don't leave people hanging the day before you are supposed to show up.
BUT
here's a discussion that kind of says the opposite of what I've said. See what you think.
Ask Annie has also covered this.