Yes, I think it ´s normally necessary to resize pictures prior to upload, at least from todays digital cameras, which have image sizes way beyond the size/filesize required for viewing on normal screen and on the web.
On
PC, I believe there are many solutions. Personally, I used
Irfanview, which is a free small image browser that also has a nice batch-resizing function. You can also use the software that comes with digital cameras, for example canon ´s zoombrowser, which has an "export" function to batch resize files. In windows Vista, I would suspect there was some native batch-resize function, but I can not say for sure ...
On
Mac, you can simply use "iphoto" with the file -> export function, to export an event or any library, to another folder. You will have to options on resizing and compression.
I might add, that we do have vision of creating a simple Imagevue-upload client, that takes the task of resizing images and uploading to your gallery at the same time.