Loading time optimization: JQuery vs. http request 2 images

I am developing a blog locally (so no url for you to view.)

I want to have the pictures on the main page in black and white and turn to color upon hovor. However, my old computer cannot handle Safari beyond 5.0.2, which does NOT support the grayscale() code.

I have a few choices:
1. Use 2 images, one in color and one in BW and place them one on top of each other, and code them so that the color one shows upon hovor. I did this, and it works nicely. But it is two http requests.

2. I can use jquery.

3. I can say, screw my lousy computer, and use the grayscale code, because of course, it really matters how others can view the page, particularly on ipads and mobile devices.

Which method would make the page load the fastest? I am hesitant of scripts because they have a tendency to hang the webpages for a few seconds.

Thanks in advance.