JPEG is the usual picture format. It doesnt use as much space, and has pretty good quality.
BMP (bitmap) is used by professional graphic artists. A 3-megapixel BMP would take up 4MB of space on the PC, vs. 1.5MB. The picture has much better color quality though.
The recommended format is JPEG, and most cameras save pics as JPEG. The website probably resizes the pictures or changes the color due to storage.
Upload the pictures to Photo Bucket
and you can upload pictures up to 10MB each! No color quality loss.
Also, there is Image Shack
, but i havent used it before, and they have less photo storage space.
Both services are free.