Outlook 2000 is part of Office 2000, & is more sophisticated than Outlook Express which usually comes installed with Windows. I'm no expert but I think that you will have to size your photos in another application. I do mine in Adobe Active Share which is brilliant for sending images by email. I think the address is click here activeshare.com
Outlook can organise your life. Unfortunately, though excellent when you really use it, it can be daunting. A much gentler approach is to start by using Outlook Express. This is really e-mail only and you can migrate to Outlook when you have read up on it. One of the 'Dummies' or 'Idiots' Guides is good. As for your photos reduce them to size by sending them as jpegs. I think the best application for this (and many other matters) is IrfanView click here. Try and keep the total size to no more than 1MB!
If so (from memory so I may be wrong) if you right click on the picture you want to send in windows explorer and select the send to mail recipient option then XP will ask if you want to compress the photo thus reducing the size before it attaches it to the mail. I think you will also get a deterioration in quality so as rawprawn says, yo may want to do this by hand so you have more control.
I think some of the replies may be a bit confused. When you say "too lagge", do you mean physically too large to fit on the screen or that the file size is too large to send.
The size of the picture on the screen is a product of the number of pixels that make up the image and is set by the quality of image taken by the digital camera. Most modern cameras are capable of 1.3 megapixels which is far too good a resolution (Too large a photo) to be displayed in a simple graphics application like Internet Explorer.
If you are taking photos specifically for sending by e.mail then reduce the quality setting on your camera to its lowest setting. This should be sufficient for your purposes.