Thanks Gazraa. I've done a properties/summary and have this info for the images in the first post;
#1 image is showing smaller than expected at 4272 pixels w x 2848 pixels h, 96 dpi & 545 kb
#2 image shows as 700 pixels w x 467 pixels h, 96 dpi & 10.1 kb [12kb on disk] - this was selected size wise in CS3 as the other explined in the other posting.
The other attempts selected/saved in CS3 [copy of first image] show at 1600 pixels w x 1067 h, 72 dpi & 801 kb [804 kb on disk] and the copy of the darker image shows the same except for a size of 1.08 mb, inc. size on disk.
My final attempt was with the full size images. The first one shows the same size as #1 above [4272 x 2848] BUT, surprise, at 72 dpi

and at 3.70 mb on disk.
Image #2 shows same as above [4272 x 2848 & 72 dpi] and a size of 4.32 mb. When i uploaded these full size images they were showing as 400 x 266

HAS to be something with Photobox.
There is an additional queer thing with this. If I am logged in to my albums I can select an image and get one on the screen showing the size as here. IF I right mouse click on the image I can view a LARGER image... So, you may be thinking why am I not linking to the properties address of this larger image? A sensible question... AND it is something I've done in the past... so why not now? BECAUSE the images then vanish from the post/forum

The "correct" way to do this with Photobox is, as per their site instructions;
Question I'd like to use an image that I have in my account on another website, but I need the link to it. How do I know which link to use to show my picture properly? Answer There are several steps that you need to follow to get the address of an image, as follows:
Links to individual images only work in Public Albums, so first you need to make the album Public. Click the Share this Album link next to the Album on your albums page. This will take you to the Sharing Wizard.; you need to click the Public option. Once the screen refreshes, you'll see a link to the album, in the format http://www.photobox.co.uk/album/123456. Copy this, and log out of your account using the 'Log out' link at the top right.
Paste the link into your browser,and visit the album whilst logged out. Next click on the Thumbnail tab to go back to the photos. Choose the photo you want to use in the other website, either the thumbnail or the larger picture that you see when you click on the thumbnail. Now right-click on the chosen picture and choose the "properties" menu item.
This will show you the address of the individual image - it's a long line of Code towards the middle of the window - this is the address that you need, so maybe copy and paste it to the clipboard so you can use it elsewhere. This is exactly the way I do the posting of images here. The "queer" thing I mentioned earlier

There Is NO option to right mouse click and select view larger image

and the "slideshow" option [logged in or out] show the same size images as here!
I've had some problems/issues trying Flikr... it tells me I have to have cookies enabled [which I have] but it doesn't acknowledge so I can't use Flikr on this laptop - HAVEN'T yet tried setting up from my desktop PC so I have that option. There are a couple of other photo hosting places I can try... as I did soon after joining here... so I haven't given up yet

One other thing with Photobox; I have a Virgin Media Photobox account - comes with having a VM broadband account - which is the one that I am linking to/from. There is also a NEW Photobox BUT [

] although I can/have set up an album there and gone through the process of changing it to a PUBLIC album so I can share images here, it remains PRIVATE when I log back in

The "logged out" link address is;
http://www.photobox.co.uk/album/54946658 - but I can not view and get the properties of an image via that link...
I have contacted their customer support and I keep recommending that I install and use Firefox to try to access that way! As I don't have any other issues with IE why, as I ask, should I use Firefox? The guy says it may help while they tackle "technical issues" with the site

Sorry for giving "another" tale of woe - I'll be getting [if not already got] a reputation for things not working out right

Frank