Regarding the large icons, have you tried changing the screen resolution to make them smaller? IF the graphics driver is correct, you should be able to change the screen resolution so things work as required. If not.....
When the operating was installed on the original computer, be it Vista or XP, the operating system detects all the current hardware and the appropriate drivers were required and installed at that time.. If the old hard drive is placed in a new computer which has a slightly different graphics card, or a different BIOS, or a different ethernet card, or any different hardware at all, it will need to have the correct drivers installed for the new hardware so they're compatible with the current operating system..
Although the model number may be the same, are you sure all the hardware is EXACTLY the same as your original computer? Either way, because you're having issues with the graphics display, you'll want to determine the actual graphics card on the new computer so you can then download and install the most current driver that's compatible with XP.. Once you get all the drivers correct, it may help the startup time as well.
Hope this helps.
I have a dell E520 dimension computer that was hit by lightening. I found a one on ebay. The only difference is that the one from ebay has Vista and mine has XP. Both have the same video card (GeForce). Mine was a small memory. I thought i would just be able to take the hard drive out of mine and put into the one from ebay and presto i would have my old computer back again. It did not quite work that way. When I put int he my hard drive the computer did turn on and i still have all my old files and stuff, but the monitor does not appear the same. I have large icons which make them look out of focus. Also, i noticed that it boots up a little slower. I thought it would boot up the same if not a little faster. The ebay computer has a slightly faster process 2.8Ghz. Mine i think is 2Ghz. What must I do to put my hard drive in the ebay computer and have the same machine i did before? Does this problem have something to do with the BIOS?