performance issues

[Lumbergh 0]

okay, so here's my issue. i've had simcity 4 since it was released, same with the rush hour expansion. sc4 used to run great on my machine, no problems whatsoever.

well, after a hiatus of not playing for a couple of years, I decided to re-install it and play again. only one problem. it performs poorly! basically it takes a while to load cities, when zoning or building there is delay (sometimes lasting several minutes!).

 I have it on moderate graphic setting and have tried lowering them with no effect. in addition, i've defragged all 3 of my hard drives numerous times, closed all unnecessary programs and even re-installed sc4 with no improvement. 

my computer is kind of old, I guess. I am running xp professional with 1gb of ram, pentium 4 1.8ghz and ATI radeon 9200 video card.

I also have the game installed on my much slower laptop (1gb ram, vista, 1.6ghz) and guess what? it runs fine. but I hate playing it on the laptop, since it is only 12.1" screen where as my desktop is 19"! lol.

is there anything else I can do short of getting a new computer? lol.