i am fortunate i traded my Wii for a New 360 with 250 GB HD, built-in wireless adapter etc....
I understand what you mean though, my buddy has the 60GB and is regretting it now, He needs space but what is more important?
Um.... deleteing FFXI until it is back up will suck. When the servers are back online you will want to play but will instead be doing the 6 hours of updates (maybe longer depending on isp & what disc collection you have). I dunno if I could do it lol.
best of luck to you IF you do delete it to play PSU