I took photo the total size of 800mb. The problem is each photo are about 3-5mb. How can i reduce all of them at once to smaller resolution and maintaining the size? If i were to use paint i can reduce it to about 100kbs. But the problem is one by one reduce will take time.
How can i do it? I do got a photoshop CS2.

Try installing Microsoft PowerToys @ http://www.microsoft.com/windowsxp/downloa...ppowertoys.mspx
You can resize one or multiple pictures by using right click.

irfran view. free, and batch convert.

irfran view. free, and batch convert.

To the original poster: use irfanview. Forget the rest. It's free and it's darn small and it's damn fast and easy.

ACDSee does the trick too. Batch resize.

1.0 How to resize ONE picture at a time
    ===================================

0.  Download and install IrfanView from http://filehippo.com/download_irfanview/
1.  Open the picture you want to resize with IrfanView
2.  Select "Image -> Resize Resample" from the menu bar OR press Ctrl-R
3.  Select the button "Set new size as percentage of original"
4.  Adjust the percentage accordingly. Try out values from 20% to 30% to get a
    suitable size. Keep in mind not everybody has Streamyx so resize the picture
    so that it's small enough to be viewed by dial-up users but still large
    enough to be viewed comfortably.
5.  Press "OK"


2.0 How to resize MANY pictures at once
    ===================================

0.  Download and install IrfanView from http://filehippo.com/download_irfanview/
1.  Make sure all the pictures you want to resize are in a common folder. Not a
    must but it'll make your job easier. Let's say all the pictures you want to
    resize is at C:\My Documents\My Pictures\Animals
2.  Select "File -> Batch Conversion/Rename" from the menu bar OR press "B" on
    your keyboard.
3.  Navigate to your picture folders at C:\My Documents\My Pictures\Animals.
    Click on the button "Add all".
4.  Make sure "Batch conversion" is selected.
5.  Make sure "JPG-JPEG Format" is selected.`
6.  Check (tick) the box that says "Use advanced options".
7.  Click on the button "Set advanced options"
8.  Check (tick) the box "RESIZE"
9.  Select the button for "Set new size as percentage of original"
10. Adjust the percentage accordingly. Try out values from 20% to 30% to get a
    suitable size. Keep in mind not everybody has Streamyx so resize the picture
    so that it's small enough to be viewed by dial-up users but still large
    enough to be viewed comfortably.
11. Make sure the box for "Preserve aspect ratio (proportional)" is checked   
    (ticked).
12. Make sure the box for "Use Resample function (better quality)" is checked
    (ticked).
13. Check (tick) the box that says "Sharpen".
14. Put in a value around 25.
15. Check (tick) the box that says "Save files with original date/time".
16. Press "OK".
17. Press "Start".

adriankhoo: press 'B' and you'll arrive at the Batch processing dialog box. Navigate your way from there. I wrote a tutorial somewhere, let me dig it out. Will post when I find it.

EDIT: Found it! This is copyrighted material with all rights reserved. Please respect them. C&C welcome.