I'm not sure about photo bucket as I haven't used it but photoshop will be able to resize your images before you upload them... I think there is a way to do this in a batch so you can re-size all your photo's in one go.
Adobe Light room allows you to export all your images in a specified size which is great when you have a collection and want to upload the whole lot... I would imagine other image library software would have similar capabilities...
I will probably get shot for this but another really simple way to do it is to highligh all the images in windows then right click and choose 'Send to Mail recipient' and this gives the option to resize the photo's, it will then open an email message and you can just save all the images back off this into a folder ready for upload.