Shrinking a picture --- and it becomes blur !!

Hello !

I do computer graphics as a hobby, and have produced quite a number of
stunning graphics. Often time though, when I shrink the graphic to put
them online, they become blurred !!

I do all kinds of computer graphics, from fractals to virtual
landscape, to sci-fi rendering, using softwares ranging from photoshop
to terragen to povray.

When I am satisfied with a certain creation, I often make a master
copy with the resolution of 8192 X 6144 pixel. Why that size? Because
that's the largest size my puny computer (dual-core 3GHz CPU running
XP with 4GB RAM) can produce within a reasonably timeframe. (Give or
take 8 hours for rendering).

As the filesize for a JPG with 8192 X 6144 resolution may go up to 30+
MB, I often have to shrink them to a more reasonable 1024 X 768,
filesize about 800 KB or so.

However, I found that when I do that, many interesting minute details
that were in the 8K X 6K pictures (even when I shrink fit it to my
1024X768 desktop as wallpaper) are GONE. In the 1024 X 768 JPG files,
all those details become blurred. No matter it's a JPG ---> JPG
shrink, or BMP ---> JPG shrink, or TIFF ---> JPG shrink, all those
details are GONE !!

I have experimented with many different graphic / photo softwares in
the shrinking process, all of them give me the same "blurring" effect.

Now my questions to all you Gurus as below ---

1.		Can you tell me of the best way to shrink a 8192X6144 size graphic
to
		1024X768 size graphic without losing the interesting details?

2.		Which software do you recommend to carry out the shrinking
operation?

Thank you all in advance !!!

Sincerely,
Lee