Вот нашел способ на сайте
http://www.wyckedone.net/2006-03-28/windows-xp-limit-recycle-bin-size/
Сам менять не пробовал, но вроде все что описано ниже имеет место быть.
Here’s how to do it:
1. Open the Group Policy Editor (on the local maching, Start -> Run -> gpedit.msc).
2. Expand (click the plus (+) sign) next to Administrative Templates under User Configuration.
3. Expand Windows Components.
4. Click the Windows Explorer folder.
5. In the right pane, double click on Maximum allowed Recycle Bin size.
6. Click the radio button next to Enabled.
7. Set the Maximum Recycle Bin size: to whatever percentage you want. Note that the arrow buttons move it in increments of 10% but you can type a number manually. The percentage must be a whole number like 2%, not like 2.5%.
8. Click Apply.
9. Click OK and exit the GP Editor.
The setting affects all volumes on which the recycle bin resides. No restart is necessary for this to take effect. If this is done on a Windows 200x domain, the policy will take effect when the next policy update or login (per machine) takes place.
Right-click on your Recycle Bin and go into the Properties. You will now see the max size set to whatever you set it to in the GP.