[R] Comparing the Means of Two Normal Distributions

[Lorenzo Isella]

Dear All,
A problem almost taken from a textbook: I have two independent samples  
(which are both assumed to come from a normal distribution).
The sample sizes are N1 and N2, the sample means are x1 and x2 and the  
sample standard deviations are s1 and s2 (the standard deviations are  
close).
I would like to conduct a two sample t-test with equal variances at  
alpha=0.05 (and then remove the assumption of equal variances).
I have come across several resources

http://bit.ly/WKGuHV
http://bit.ly/WKGwzG

but the difference here is that I have access only to the N,x and s for  
the two samples, NOT to the results of every observation (i.e I know for  
instance N1 x1 and s1, but I do not have the corresponding list of N1  
values).
Many thanks for any suggestions.
Best Regards

Lorenzo