You can tweak the product details columns widths to make a bit more room...
eg. if using product page style 1, edit skin/reboot/customer/main/product_style_1.tpl
Replace <div class="span5"> with <div class="span4">
and...
Replace <div class="span7"> with <div class="span8">
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If using product page style 2, edit skin/reboot/customer/main/product_style_2.tpl
Replace <div class="span7"> with <div class="span8">
and...
Replace <div class="span5"> with <div class="span4">