Jules,
If you are going to continue to shoot indoor events, I would suggest you at least invest in an Olympus FL36 flash. I believe that you will also notice very soon that your flash is not powerful enough. I started with an FL36 and I soon learned that I could still use more power so I upgraded to the FL50. My daughter went through the same routine. So if you shoot a lot of indoor stuff the FL50 is the ticket. The FL36 and FL50 are specifically made for the Olympus line so no compatibility issues. Until Olympus came out with their new E3 camera they have had problems shooting at high ISO settings, over iso 400, making low light situations harder to shoot. This should also be considered in securing a good flash for your 510. Hope this helps...
Gabe