I cant help on High definition camcorders as i've just got my first £152 JVC SD camcorder and I'm still learning
Wish i had this 4 years ago in summer 2003 when Concorde was flying as i could have got priceless movies of Concorde taking off and landing. If you ever saw Concorde taking off you'll know how awsome that plane was, makes the "new" Airbus A380-hippo look "old fashioned" and very very slow.
With camcorders you could try JVC, Sony or Canon they all do High Definition ones, best thing is to go to your local camcorder shop and ask the salesman what he recommeds for around £1500, play with that in the shop and see how it feels.
Then go on the internet and see if you can get a better deal on that camcorder from a well known and respected website.
As for your PC hanging what spec is it (processor, memory etc) ?
There are many different reasons behind it hanging. It could be a viruses or spyware running in the background which are sapping the PCs resources.
Use Adware and Spybot to find these and get rid of them.
Run anti virus to clean your PC of any bugs
Buy Norton utilities or system works and use that to fix any bugs in the PC.
Defrag your hard drive to make sure its ok.
It could also be things like anti virus or firewalls running in the background which could also be sapping the PCs resources.
Before you process any video disconnect the modem so you cant access the internet.
Press CTRL + ALT+DEL keys, find out which processes are running in the background, Get rid of them and then start to process any videoes.
That way your entire PC will have all it resources for video processing and your PC should be ok.
If your going to buy a new PC get one with Intels dual core processor + as much memory as you can afford + firewire port + 2 hard drives (one as your C drive and one for video processing), make sure the video processing one is fast and 300gb or more as 1hr of raw footage from camcorder takes up around 50gb in AVI format.
If your seriouse about video processing the more space you have the better.