Partition failure, please help!

The data is most likely gone, though you should try several different recovery programs first and see (some work better than others).

It's strongly recommended to create an Entire Disk Image backup before making partitioning changes, especially when using the Merge/Split features. I have expressed my concerns many times to Acronis about this and tried to get them to place a warning in DD to create a backup. A backup should be made regardless of the partitioning software being used. There is always the chance of data loss when making partitioning changes.

Yea it was very stupid of me to not backup beforehand, am kicking myself now as the last backup I did was at Christmas! So will have lost everything I've been working on since then, such a moron :(
I've tried a couple of other programs and the data is always corrupt in the same way, so am guessing I'm buggered. Going to send it off for a diagnostic anyway to see if anything can be done by the pros. Think it may be something to do with either sector or cylinder sizes being changed by Acronis. See what you think of these images (disk0 is the broken drive). The values are way different to that of the partitions on my second drive (disk1)..

The first partition looks like a standard System Reserved partition (Windows boot partition). The second partition entry doesn't look valid.

When DD is making Split/Merge changes, the partitions are in limbo. It's very easy for data to get lost if anything goes wrong during the process. That's why it's so important to make a backup first.

Let me ask you something... If DD had displayed a warning message recommending that you have a current backup of the drive before committing the changes, would you have created a backup? Would you have appreciated the warning or would it have made you feel less safe using DD? -- I've been trying to get Acronis to add this, but they don't seem to agree that it's necessary or even desired.

That is true if the process gets interrupted as it has in my case, otherwise (if you know what you're doing) playing with partitions should be fine. In answer to your question, on one hand most people editing partitions with programs like Acronis do know the risks involved, so a warning might not be essential. But on the other hand it might remind the user of an unfortunate incident where they didn't back up (!), prompting them to do it..
RE: Second partition - I was thinking about editing those values to correspond with my other HDD but I'm not confident about it, so will get sent off this week and keep fingers crossed :)