Unless the two computers and printer are fairly new, the card readers are probably not SDHC - but just SD card readers.
Take your memory card to your local photo printer location and see if they can see the files with their equipment.
If so, have them copy the photos to a CD for you.
WalGreen Pharmacy and WalMart will do this.
They usually only charge a couple of dollars per CD.
You may want to consider buying a SDHC card reader.
I have a Canon Powershot SD780 IS that I have had for 9 months. I can take pictures and video. I can see all the pictures and video on my camera. Unfortunately I can't download the pictures anymore. The memory card is a SanDisk 4GB SDHC. Up until February, I was able to download pictures/videos to my Mac. I have tried different cables, another Mac and a PC. I have tried a card reader and a printer (that reads from the card). Nothing will recognize the card. Do you have any suggestions to help me download my pictures?