I think that you might mean "vs. an HTPC", correct?
Yes, many external scalers work great and some are even specially configured for D-ILA use. Your best bets will probably be a Rock, Faroudja NR, Crystal Image or Vigatec scaler...in approximately that order.
An HTPC is a great choice as well, but you will lose a bit of the WAF unless you spend some time setting it up to be really simple to use.