From personal trial and error experience with converting an Acer, a couple of quick tips:
1) Format your SSD with FAT32, not NTFS -- it makes a huge difference to the write-speeds, which is where SSDs lag behind.
2) Once converted, turn off the main suspects which will slow down your drive, notably Pagefile (if you have enough RAM), System Restore and even the Recycle Bin if you don't need it.
3) Disable Hibernate, which will colonise a huge chunk of your tiny SSD.
4) Install one of the freebie caching systems which AAO users have found can speed you up enormously: FlashPoint is brilliant and halved my own drive access speeds. See one of the most popular forums for details of this and many other AAO or general netbook issues: http://www.aspireoneuser.com/forum/
Installing XP on a small SSD can be a huge disappointment without the above! It will run like the proverbial snail having a bad mobility day.... With the modifications, you can get performance pretty much equal to that of the HDD model, which ain't bad given the SSD's lower power drain and increased robustness. Good luck!
I wonder if there's some confusion here? I thought Linux was only supplied on the SSD version?
If however you definitely ARE getting a HDD version, then pretty much none of my advice applies, as XP runs beautifully on the version of the AAO which Acer supplies, pretty much as is. You might like to add some RAM -- but I would suggest you don't let the average computer shop near this job as even Acer say it is, theoretically, a factory installation. If you are reasonably nifty with a screwdriver, and confident, you can do it yourself with the help of instructions found on the AAO forum I mentioned earlier. In essence though it pretty much involves dismantling the machine to do it, not a job for the faint-hearted.
Incredible Deception sells 1GB of RAM for the AAO for around R200. AAO Forum postings all suggest the machine may not recognise much more than this, so don't waste your money buying an even bigger stick.