I am interested in a wider auto-bracketing range for HDR work.
5D has only 4EV, whereas 1D has 18EV maximum  range with autobracketing.
The new Nikons are better than 5D in that respect, with 8EV.

But if the successor to 5D brings an improvement there, plus weather sealing plus dust cleaning, I think I am going to start saving for that camera.

I've been getting a lot of rejections on Panthermedia.  They are more strict on my images than even Dreamstime or Fotolia, which is ridiculous. 

I find Fotolia ridiculous, they started to reject my images that have been accepted by SS, IS, and DT. Maybe FT doesnt want outdoor pics, and that's all I do..., but when they list multiple rejection reasons (noise, out of focus, lighting, etc. etc.) for images accepted by the major sites, I find it disrespectful. The images might not be brilliant, but surely they are not so bad. I gave up on uploading to FT.

As for Panther, please take a look at their list of lesser wanted subjects:
http://www.panthermedia.net/index.php?page=cms%2Fpages%2Fdisplay2.php&cms_id=209&blanc=on

It might be wise to stay away from those subjects, to improve the acceptance rate.
However, the say they don't need photos of landmarks, but all of the pics that I uploaded there were landmark photos, and they were accepted. I just tried to make them stand out from the rest, uploaded mainly HDRs  or nightshots.

BTW, graficallyminded, thank you for your comment on Mostphotos, actually that pic was also accepted by Panther.

I think Panther does have some potential, their price structure is decent, much better than the micros, so just a couple of sales means some nice income. I read also a German micro forum where some members report regular earnings from PM.

If anybody would like to join Panther, here is my referral link:
http://www.panthermedia.net/?aff=126849

I have a rather microscopic port there, 6 images only, all cityscapes (joined PM this month).
Acceptance rate: 100%, 3 pics got reviewer's recommendation.
Sales: none so far

I would recommend getting more RAM.
CPU is secondary as far as PS is concerned.
Graphic Card is not that important for PS.
I assume you run XP, because on Vista Photoshop might really suck with 1GB RAM .