On the PC I use to fool around with as a sort of educational toy, I got myself into a real "fix" that I can't seem to unfix. As with quicksand, it seemed the more I tried to correct something that wasn't working the deeper a hole I got myself into. So now when I start up, I get a message saying "invalid partition table." The fixboot format and fixmbr commands on my WinXP CD haven't been of assistance. A repair install didn't seem to work either. A tech friend thinks I may need to acquire another hard drive and then copy the entire partition from this drive to that since I can't access so far.

Any feedback appreciated.

If you have an "anti-virus rescue boot disk" [on which is kept a backup of your "Partition Sector"], you could use it to re-build that sector with it's "Partition Record".
It may have been corrupted by a virus.
If you used the backup copy of the MBR [which may have been corrupted] to replace the main copy, then it wouldn't help in that case.

If you have a clean backup of the C: drive you simply re-format the C: drive and restore the backup.

If you have neither of these, then I guess it won't be quite so easy to fix.
I'm no expert on this, but I like the idea of installing a clean, new HDD as master, installing Windows anew, connecting the old HDD as slave and scanning it for infection from the new drive.
Or transferring all the needed data files, then erasing its contents and re-partitioning and re-formatting it.

Hopefully someone who knows about such things will come along.

There are four partition table entries in the MBR. Each one is 16 bytes in size and they occupy bytes 447 thru 510 of the 512 bytes that make up the MBR. Fixmbr rewrites bytes 1 thru 446 but doesnt ever touch the partition tables unless the signature code (bytes 511-512) is invalid - in which case they are zeroed. Fixboot rewrites the Partition Boot Sector. So neither of these commands would be expected to correct the partition tables themselves.

The hex offsets for each record:
E = Boot Indicator (eg the Active Partition)
F = Starting Head
0-1 = Starting Sector/Cylinder (6 and 10 bits respectively)
2 = Partition Type
3 = Ending Head
4-5 = Ending Sector/Cylinder (6 and 10 bits respectively)
6-9 = Sectors preceding the partition
A-D = Length of partition in sectors

As long as you know the partition structure of the drive with the size and type of the partitions on the drive then (using a hex editor such as WinHex or MS DiskProbe) you can edit these tables so that they are no longer invalid.

Alternatively, copying the partition to another drive is likely to work since the copying utility should normally rewrite the new partition table appropriately to match the copied partition.

You can also use data recovery software to recover files on the drive.

It all depends what you want to achieve. If you just want to experiment with editing the tables try grabbing diskprobe, etc and read up on the structure of the mbr and the partition tables.

You can grab DiskProbe from a Win2K installation CD or from http://www.petri.co.il/download_free_reskit_tools.htm It's not the easiest utililty to use but is good to help with the learning processes none-the-less - and its free.

Well, I just went ahead deleted and formatted the drive and reinstalled XP all over again. The ghosted image which would have been a time saver(as far as not having to re-install and re-download the pre-existing files)didn't work out either.

I wouldn't expect that [re-formatting] to work.

You'd need to RE-PARTITION to fix the partition table.

Which is what essentially I did(re-partitioning that is) by deleting all the prior partitions, formatting, and just re-installing XP.

In reflecting on this most recent "fiasco", I think my dabbling with the FDISK utility, in particular, re-making the first partition active(which may very well have been active already)was the likely cause of this.

Check this out
http://www.pcguide.com/ts/x/sys/booterrGBER31-c.html