Buying an expensive computer. Is it worth it?  

I think you should do what your uncle wants.
As you said earlier its his money ... so you should do as he said...

it depends from your daily usage of your computer,the purposes you are buying it and so even performances you are waiting from your new computer as well!!So i think expensive one naturally have a strong or high configuration and this can be ok,if the hardware is good,for many years!!So surely models and technologies during the time will change often..but if you can buy now the computer really suitable for your needs it is no necessary to buy always the new one!!
Personally i like expensive computers...because they have a really improved configurations and so normally i judge a computer not from the style or dimensions but from a cpu,ram,graphic cards,disk space,ports and so on...and surely in many cases all characteristics especially strong processor is costly...Naturally if your uncle is really generous and want a better pc for you..may be it can be good because if you will buy a quality one today...you won't buy another one for many years!!On the contrary there are many people that buy today a cheaper computer...and in 1 year and half they are searhing for a new one...so.in some cases the first option should be better!!

I don't think it is worth it if the one you found has everything you need because if you don't need all the extra stuff on the more expensive one than it is not worth your money.

If you need a computer with good configuration then its obviously an expensive one.It depends on your what type of computer you want..Good and high configuration is always a expesnsive.if you say after sometime there will be a newer computers available so i would say better buy a computer as your Uncle said.
expensive means better computer,it means it can compete with new models..:)

buying an expensive computer doesn't mean that it'll perform better.