@Elrohir: van Basten actually didn't say he'd only replace the yellow-card players, he said 'we have 23 more or less equal players, so we don't have a b-squad at all'... I am guessing he'll give the ppl with a yellow card a rest, Robben won't play (as he is still slightly injured), v/d Sar will probably be spared as he has had a long and hard season, some ppl will get the chance to get a few minutes in.
As far as I can tell Sneijder, v/d Vaart and van Bronckhorst looked fittest of all players in the first two matches... Personally I'd keep Kuijt on because he played really well in the first two and deserves to play as often as possible and van Persie can use any match he plays as it will only make him fitter and better at this point... If he holds on to the same system of play I hope van Basten uses the following squad:
1) Stekelenburg
2) Melchiot (if fit, otherwise Ooijer or Boulahrouz (if Boulah, then Bouma plays centre back)
3) Heitinga (played all qualifier matches, yet no minutes in the Euro Cup yet)
4) Boularhouz (strong and fast, killed di Natale, im confident he'd do well against Mutu)
5) de Cler (good replacement for van Bronckhorst, will assist in all attacks on the left)
6) de Zeeuw (played all the qualifier matches, yet no minutes in the Euro Cup yet)
7) Engelaar (its his first tournie give him some fun, plus he was incredible against Italy!)
8) Kuijt (can also be full back
)
9) van Persie (any match he plays benefits him a great deal to become more fit and better, he did well being substituted in in the first two matches)
11) Sneijder (one of the best players of the tournament thusfar)
10) Huntelaar (its not van Nistelrooij, but still a very decent striker)
Obviously this team would be different to what we've seen in the first two matches. Then again, the opponent is different too... Romania is weaker on midfield than Italy and France...
Goalie: Stekelenburg is a decent replacement for v/d Sar, but obviously v/d Sar is waaaaay better... Yet I wouldnt take any chances with v/d Sar after a long season in which he experienced a good number of injuries already. The Dutchies face (hopefully) three hughely important matches in the quarters, semi's and final; risking anything with v/d Sar would just blatently be dumb. I'd rather thave v/d Sar in the quarter finals than Stekelenburg any day.
Defence: Heitinga and Boulahrouz are as good defenders as Mathijsen and Ooijer, but they have different qualities (in this case more speed in the centre against Mutu)...
On midfield Afellay is a good choice to replace anyone halftime really (see him against Italy?! he did well).. The defensive midfielders have the strong and powerful Engelaar (anyone see those Italian midfielders doing anything?) combined with the versatile de Zeeuw who seeks more ellegant sollutions than de Jong (plus he is more dangerous when he advances towards the box with the ability to give a good cutting pass and a powerful shot)
The forwards would still have enough quality (and creativity!) to make most defences in the tournament shiver with van Persie on his preferred position, Kuijt with a lot of room to gallop and Sneijder allowed to do whatever he sees fit (with his current form there it would be a crime to restrain him). Huntelaar did well this year in the clubmatches and has proven himself internationally as well.
I'm still rooting for the Dutch to win and beat Romania... Czech republic helped the Dutch advance in Portugal 2004 with their last round win over Germany (even though they were already through no matter the result), the Dutch should try to do the same thing and not throw in the towl before the match. Yet it wouldn't be wise to use players who are in a somewhat fragile state (Robben, v/d Sar) or had a long season. Underestimating Romania wouldn't be wise, they are very dangerous as the Dutch have experienced in the qualifiers and seen against Italy and France... I'm hoping for a 3-1 win though, just cuz we're on a roll 
Sexyness...