I also had the same dilemma over the weekend. I passed SCJP this passed Saturday and now was wondering whether to go for SCWCD or SCDJWS. I went through lots of threads and finally decided to go for SCWCD for the following reason :-
1. SCWCD is easier than SCDJWS (which is considered to be the toughest one) and also its scope is less, therefore you could clear it in much less time.
2. The best book is available - Head First
Servlets and JSPs by K & B & B. The good book (from Osborne)is still in works for SCDJWS, I dont expect it until next year.People have been waiting for it for long.
3. More companies today use Servlets/JSPs than SOAP/WSDL/UDDI etc therefore more job opportunities.
4. If you want to put nice words on your resume and that too quickly, go for SCWCD now, and then go for SCDJWS.