Vista - Install fail - help please

I downloaded RC1 and burned a DVD and backed up my system
I used Partition manager to re-organise my disk and created an empty 50Gb
(Drive G primary partition. I also have ‘Recovery’ (primary) and a Dive C
(primary, active) and an extended partition with 3 logical drives. Tested and
XP still OK.

I ran the Vista install, selecting to install in the G partition, with
update enabled.
Vista installed and as part of the install created a dual-boot menu
Selecting Vista worked and Vista was functional – some driver issues with
Sound, TV and wireless net card but these are unimportant at this stage as I
rarely use them.

After having a ‘play’ I shutdown in order to re-boot in XP. I selected the
‘Old Windows System’ option from the boot menu.
Error – white text on black screen – ‘<windows root>\system32\hal.dll
missing or corrupt’
Tried again – same, Tried selecting Vista – OK
Now what?
Tried using backup boot recovery to recover drive C backup. Completed
Tried re-boot – same problem.
Decided to re-install from XP CD
Boot – blue screen of death – ‘stop’ error – caused by pci.sys.

I eventually got XP back using Manuf's recovery CD