How can I do it to re-size an image?
Say, I've got a 320x240 image and I wanna re-size it to 50x50, keeping every single detail. How can I do that in Paint, please?

To resize an image in paint, you'd have to go to Image > Sketch/Skew and use "Sketch," which works percentage-wise so you'd have to figure it out... If you want to keep the quality of the original picture, you'd have to do it in a quality program like Photoshop or something.

I can resize it for you when I get home tonight.

You could try using IrfanView.

IrfanView Homepage

if u have phtoshop, u can change the settins to watever u want

on the menu bar image<image size