Hi, I've had a Sony DCR-TRV245E for 2 years (since Sony had to replace my TRV235E when the internal battery & charging system broke... it's amazing that they took several features off when they "upgraded" the 235 to the 245, but it's still been a great camcorder for the money!).
As Mark suggested, to get full quality video onto your PC, you'd need to use Firewire, rather than the USB cable you've got. Have you got a firewire connection on your PC? If not, you can get a firewire card for the computer & connecting cable very cheaply!
If you want to use USB, I'm sure you could get the USB Driver - and Sony's Image Mixer software - either from their website or if you phone them up. If you didn't have any luck, I'm sure they wouldn't mind me doing you a copy of my CD and sending it to you!
The Image Mixer software is a very basic movie editing suite, but to be honest I've never even loaded it onto my PC, because the Windows Movie Maker 2 that comes with Windows XP (in the "Accessories" folder) actually looks better anyway. I believe it will capture straight from the camcorder via firewire (you'd still need the driver if you're going to use USB), and do some basic editing (transitions, titles, music, etc).
If you then wanted to take the editing and DVD authoring a step further, and end up spending more money, there are several other programmes out there for around £35-£50 (and upwards!), which will do a bit more advanced editing. I use Ulead Video Studio, but the different alternatives (including Pinnacle Studio, Sony Vegas, Adobe Premier Elements) are weighed up on several other threads on here. I think you can sometimes get the programmes bundled up with a firewire card & cable "all-in-one" if that's cheaper, but see what Mark's said here:
Firewire install - is it easy???
Good luck with it all anyway!