motif search

Hi,

I am very new to R and wanted to know if there is a package that, given 
very long nucleotide sequences, searches and identifies short (7-10nt) 
motifs..  I would like to look for enrichment of certain motifs in 
genomic sequences.

I tried using MEME (not an R package, I know), but the online version 
only allows sequences up to MAX 60000 nucleotides, and that's too short 
for my needs..

Thanks

A