Hi Mrbobcat,
From an attractive 25 year-old girl's perspective: Definitely go for it! If you never try, you'll never know. Most of the girls that I know are attracted to older guys (not like 20 years older), but more like 3-8 yrs older than they are. Also girls like it when a guy can approach them and not just "adore" them from afar. This shows confidence - and that's what most (if not all) girls find attractive in a guy. So, you've got nothing to lose (except more time and more hair :) Even if it doesn't work out with this one, don't give up, just approach girls with confidence - you will see that it does really work! Good luck!