two resistors in series with the same stats would do the trick. Honestly at this point I'd look for "dead" xboxes from the same generation and pick one up for $5
R10 is a 68k, 5% rated around 3W or so. You can bet that if it's fried, IC1 is probably toast, and who knows what else in there. The likelihood of it just up and dying on it's own are very slim. Unless you're proficient at troubleshooting SMPS and are aware of the dangers involved, you're really better off just getting a replacement.