You have to ask yourself why you want to upload the photos online. If its for backup and archiving (to save space on your harddrive), then your best bet would be to upload it at the maximum possible quality.
If you just want to share your photos among family and friends, then re-sizing it to something around the 1920x1080 (generic wallpaper size) is probably good enough (most people's screens aren't higher res than that). 1024*768 is a bit on the small size (the max for the tinypic site).
Aside for easy viewing and saving space, the only reason i'd reduce image size is to make it quicker to upload images if you are on a slow internet connection. If you connection is relatively fast then its not a worry.
Check out this threadthis thread about backing up photos if its relevant to you. I'd personally say that harddrives (500GB plus) only set you back about $50 these days so it might be worth while investing in one of these if you aren't shooting full time.
Hope that helps! Cheers,