I have a memory card that hold 700 or so pictures,

2 things the memory card and the recovery of your files.
Your camera was produced in 2005 and in those days only MMC and SD cards could be used. A few years later the SDHC came and 2011 SDXC came. devices are downward compatible. So newer cameras can use also SD cards. But older cameras can't use newer memory cards. Even a SDHC can't be used in your camera. And although I managed to buy a 4GB SD card a few years ago, now they only produce SDHC and SDXC cards. Yes be aware a 1 GB or 2 GB card now ar most of the time SDHC.
Check your card, when it says SDHC, don't try to us it, it won't work.

Then the photos from your parents. It looks we never have taken enough pictures.
When you have old memory cards, please don't use them till you checked if there are still "deleted" pictures on them.
Deleted is most of the time just clearing the pointers to the files. The files in most cases stay on the card.
Try to download some software from this site:
Memory Card Data Recovery
Then run the software, when you have a memory card in a memory card reader and see if it can find "deleted" pictures. Be aware when you use a card with "deleted" pictures, the space that came free, will be used to put new pictures there. SO don't use the cards till you did recover everything to the computer.

There are more free recover program's. I have one form Sandisk, I got it for free with a sands memory card. Login on that site to and see if they still have free program's for Sandisk users.

Success

You may use any brand xD Picture Card. The key is that it be an "xD" card, not the far more common "SD" card.

According to the specs on Canon's web site, the IXUS 700 works with SD cards, not SDHC cards. SD cards are limited to 2GB in size (there are rare 4GB SD cards, but they tend not to work in SD devices).

Of course, it's your call as to how definitive any manufacturer's web site touting their product might be.

The A530 is designed to work with SD cards, not SDHC cards. You'll need to go with cards 2GB and smaller.

I had a look and it seems 1GB is about the Maximum? yes Sandisk is a good brand. Frankly anything that works well is OK.
Buy a good brand of card ... SanDisk is my favorite.
Kodak would certainly be a good choice too.
Don't buy it on eBay, as there are too many counterfeit cards available on eBay.

A Tip:
If you use a card reader, you will need a SDHC card reader if you use a SDHC card.
Most older card readers can not read a SDHC card.

Tip number 2:
Always format a new card with the Camera before taking any pictures.
You will find how to format with the camera in the camera User Manual.

Some cameras cannot handle over 2GB memory cards. If it works fine with 2GB card - stick to that. If some other A620 you know operates with 4GB card, take yours to repairs.

This Canon uses an SD memory card (previous Canon used CF cards).
The SD memory card has a "slide switch" that locks the card.
Look at the SD memory card and move the switch back and forth, then switch it all the way to the UNLOCK position. Put back in the camera and format the card, then use it.

Since this is a 10Megapixel camera, use at least a 2GB SD memory card. A 2GB SD card will hold 700 pictures, or so, in the best setting.

Hope this helps!

No, the A420 does not have internal memory. The card that came with the camera is only intended to allow you to try the camera to make sure it works. You should really purchase a new SD card. New ones these days are literally capable of holding hundreds if not thousands of pictures, and cost less than $7. Here's an example:

http://www.amazon.com/SanDisk-Memory-Card-SDSDB-2048-Package/dp/B000J47W12/ref=sr_1_1?ie=UTF8&s=electronics&qid=1231445448&sr=1-1

after you have copied or removed the pictures from the card, insert it into the new camera and run the format, which will erase the card.

Have you tried to format it with the camera? It may need formatting in order to unlock it.