SD Card Copying to problem

[#1]

My Mum has one of those digital photo frames and she asked me to add some of my digital photos to it!  It uses a 1GB Sd Card and there is ample room on the card for my photos to be added on but for some reason whichever method of putting the images on the sd card I am finding I can only get a certain number on before it starts showing an error! I have attached the 'pop up window' with the error details on- it shows the error as this 0x80070052 the directory or file cannot be created - butI can't find much help on Microsoft about it!
Given its a 1gb SD Card accordingly to literature with the card if they are 4mp pictures it could hold 762 jpegs, the most I can get on my card is 177!! I have downloaded all the existing photos on the card to my laptop and along with the new ones we want to add I have resized the jpegs 640x480 - including those already on the card but I am still stuck at 177! Aaaaahhhhh!!! I have tried another sd card from my camera and the same problem happens with that one as well!
I have tried using windows Vista 'send to' the sd card and also Canons ZoombrowserEx to copy the photos to the card, and the same again with a Fuji Finepix Viewer! I have an integrated sd card reader and also a USB card reader, using either of those methods is giving me the same problem! Am I doing something wrong??
I don't know what else to do, I'm totally stumped if someone can help me with this please, I will be so grateful,

[#2]

Some advice on Microsoft Technet seems to suggest its worth formatting the card using FAT32 - a few people have reported this solving the problem.
Another workaround is to create a folder on the card, and then put the files into the folder, however this prevents some photo frames from seeing the images when in slideshow mode.
Here's the thread I found;
http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=2470444&SiteID=17
A thread on SanDisk's forums seems to corroborate the advice:
http://forums.sandisk.com/sansa/board/message?board.id=shaker&thread.id=280

[#3]

James, You superstar!!    Thanks the Fat32 advice has worked perfectly and my Mum now has sooo many photos of my Niece and Nephew to coo over!!
Thanks I couldn't have done it without your help - what would I do without this forum and all its clever members to help me out of my messes!

[#4]

Always a pleasure to be of service