A entry level full suspension bike starts around $1500 and good ones in the $2000+ range. So you may want to start with a HT in case you don't really enjoy off roading as much as you'd think...this way you don't spend so much on a bike just sitting in the garage.

Once you learn how to handle the HT and you think you're ready to upgrade then go demo a FS (a good one). Take the demo FS or even try a few of them and see how it rides. If you like it that much better, then get one.

I've been riding a HT for 5 years and was ready to upgrade to a $1700 HT. Just to see, I demo'd two full suspension bikes in the $2500 range and left with the wow factor. Then I did the same for my wife and had her demo a FS. So, I walked into my LBS ready to spend $1700 and left with 2 FS bikes and spent $4500. BTW, we got 2008 Stumpjumper FSR's...