On the web?

Answer:
Not without breaking the law.

The GNU Image Manipulation Program is a good, free alternative.

http://gimp.org/

Answer:
As David D has already mentioned, you cannot legally get a fully version of Photoshop for free. You might get a 30-day trial for free but after that you’ve to pay for it. A much superior solution would be to download GIMP (also mentioned by David D) which is completely free. It has almost all the features of Photoshop that most photographers need. Give it a try.
Answer:
You can download the trial version of Photoshop 7.0 for free and not the complete version, not atleast the legal copy.

But there are some substitute softwares which are simile to Photoshop 7.0 which are free (basically open source softwares). If you want to try these then you can find it out in - www.osalt.com.

Answer:
There are several naughty ways. I'm not suggesting you do this but some people install a bit-torrent client, like mu-torrent, on their pcs:

http://www.utorrent.com/

and then go to bit-Torrent tracker sites like Mininova

http://www.mininova.org/

and Pirate Bay

http://thepiratebay.org/

spicifically to locate torrents that grant them to download all sorts of things for free. I'm not advocating that you do this yourself but perhaps you might like to do some private “research” and look into the aforementioned technology further.

Beware of viruses!

Answer:
Naughty girl… shocking.
Answer:
yea, use gimp. it's really good.