Hard disk partition problem under XP

Hi, I have bought some weeks ago a new PC with XP Professional. I added it my
old hard disk, which had 3 partitions. As I not longer needed them, I copied
all the information in the new hard disk, and in the older one I eliminated
the partitions, created a single one and formated. And put back on it the
information (only data, not a bootable partition or something like that).
Yesterday, three weeks later, I installed the broadband connection (first
time I connected this PC to the internet), the antivirus and all the updates
that Windows Update indicated.
Today, I was surprised seeing the old hard disk in one of the intermediate
states that existed during the partitions modification: three partitions
(more exactly, two primary plus free space) and no information. My questions:
1) how is it that possible, if I used theold hard disk for three weeks with
no problems (retrieved, saved, ...)??? Could it be related to the Updates?
2) moreover and more important: may I recover my data??? How?

Thanks a lot in advance,

Adeline